refactor: update benchmark results and configuration for improved performance in go-migrate

.env.example

@@ -1,2 +1,29 @@
-PG_FROM_DB_URL=postgresql://postgres:password@localhost:5432/db
+SOURCE_DB_URL=sqlserver://sa:password@localhost:1433?database=master&packet+size=32767&loc=UTC&dial+timeout=120&connection+timeout=120&KeepAlive=30
-PG_TO_DB_URL=postgresql://postgres:password@localhost:5432/db
+
+# used only when SOURCE_DB_URL is not set
+# SOURCE_DB_HOST=localhost
+# SOURCE_DB_PORT=1433
+# SOURCE_DB_NAME=master
+# SOURCE_DB_USER=sa
+# SOURCE_DB_PWD=secure_password!123
+# SOURCE_DB_OPTIONS="packet+size=32767&loc=UTC&dial+timeout=120&connection+timeout=120&KeepAlive=30"
+
+TARGET_DB_URL=postgresql://postgres:password@localhost:5432/db
+
+# used only when TARGET_DB_URL is not set
+# TARGET_DB_HOST=localhost
+# TARGET_DB_PORT=5432
+# TARGET_DB_NAME=db
+# TARGET_DB_USER=postgres
+# TARGET_DB_PWD=secure_password!123
+# TARGET_DB_OPTIONS=""
+
+LOG_LEVEL=INFO
+
+AZ_STORAGE_ENABLED=false
+AZ_ACCOUNT_NAME=
+AZ_CONTAINER=
+AZ_ACCOUNT_KEY=
+AZ_USE_HTTPS=true
+AZ_SERVICE_URL=
+AZ_PREFIX=

.gitignore

@@ -4,6 +4,7 @@
 *.dll
 *.so
 *.dylib
+bin/
 
 # Test binary, built with `go test -c`
 *.test
@@ -26,5 +27,6 @@ go.work.sum
 
 # Editor/IDE
 # .idea/
-# .vscode/
+.vscode/
 .temp
+.atl

Makefile

@@ -0,0 +1,80 @@
+.PHONY: build build-linux build-windows build-all clean help
+
+# Variables
+BINARY_NAME=go-migrate
+CMD_PATH=./cmd/go_migrate
+OUTPUT_DIR=bin
+VERSION?=$(shell git describe --tags --always --dirty 2>/dev/null || echo "dev")
+BUILD_TIME=$(shell date -u '+%Y-%m-%d_%H:%M:%S')
+GIT_COMMIT=$(shell git rev-parse --short HEAD 2>/dev/null || echo "unknown")
+
+# Flags de compilación
+LD_FLAGS=-ldflags="-s -w -X main.Version=$(VERSION) -X main.BuildTime=$(BUILD_TIME) -X main.GitCommit=$(GIT_COMMIT)"
+
+# Default: compilar para el SO actual
+build: build-$(OS)
+
+ifeq ($(OS),Windows_NT)
+build-native: build-windows
+else
+build-native: build-linux
+endif
+
+# Compilar para Linux (sin CGO para máxima compatibilidad)
+build-linux:
+	@echo "Compilando para Linux..."
+	@mkdir -p $(OUTPUT_DIR)
+	CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build \
+		$(LD_FLAGS) \
+		-o $(OUTPUT_DIR)/$(BINARY_NAME)-linux-amd64 \
+		$(CMD_PATH)
+	@echo "Binario creado: $(OUTPUT_DIR)/$(BINARY_NAME)-linux-amd64"
+
+# Compilar para Windows
+build-windows:
+	@echo "Compilando para Windows..."
+	@mkdir -p $(OUTPUT_DIR)
+	CGO_ENABLED=0 GOOS=windows GOARCH=amd64 go build \
+		$(LD_FLAGS) \
+		-o $(OUTPUT_DIR)/$(BINARY_NAME)-windows-amd64.exe \
+		$(CMD_PATH)
+	@echo "Binario creado: $(OUTPUT_DIR)/$(BINARY_NAME)-windows-amd64.exe"
+
+# Compilar para ambas plataformas
+build-all: build-linux build-windows
+	@echo ""
+	@echo "Binarios compilados:"
+	@ls -lh $(OUTPUT_DIR)/$(BINARY_NAME)*
+
+# Compilar para Linux arm64 (opcional, para Raspberry Pi, etc.)
+build-linux-arm64:
+	@echo "Compilando para Linux ARM64..."
+	@mkdir -p $(OUTPUT_DIR)
+	CGO_ENABLED=0 GOOS=linux GOARCH=arm64 go build \
+		$(LD_FLAGS) \
+		-o $(OUTPUT_DIR)/$(BINARY_NAME)-linux-arm64 \
+		$(CMD_PATH)
+	@echo "Binario creado: $(OUTPUT_DIR)/$(BINARY_NAME)-linux-arm64"
+
+# Limpiar binarios
+clean:
+	@echo "Limpiando binarios..."
+	@rm -rf $(OUTPUT_DIR)
+	@echo "Limpieza completada"
+
+# Ayuda
+help:
+	@echo "Comandos disponibles:"
+	@echo ""
+	@echo "  make build              - Compilar para el SO actual (Linux/Windows)"
+	@echo "  make build-linux        - Compilar para Linux x86_64"
+	@echo "  make build-windows      - Compilar para Windows x86_64"
+	@echo "  make build-linux-arm64  - Compilar para Linux ARM64 (opcional)"
+	@echo "  make build-all          - Compilar para Linux y Windows"
+	@echo "  make clean              - Eliminar binarios compilados"
+	@echo "  make help               - Mostrar esta ayuda"
+	@echo ""
+	@echo "Ejemplos de uso:"
+	@echo "  make build-all          # Crear binarios para ambas plataformas"
+	@echo "  make build-linux OS=    # Crear solo para Linux"
+	@echo ""

README.md

@@ -0,0 +1,92 @@
+# go-migrate
+
+Migrador de datos entre SQL Server y PostgreSQL con procesamiento en paralelo.
+
+## Compilar
+
+```bash
+go build -o go-migrate ./cmd/go_migrate
+```
+
+## Uso
+
+```bash
+./go-migrate [opciones] [<ruta-config>]
+```
+
+### Opciones
+
+| Flag | Descripción |
+|------|-------------|
+| `-config <path>` | Ruta al archivo de configuración YAML. También se puede pasar como argumento posicional. Si no se indica, se busca `config.yaml`. |
+| `-validate` | Compara la cantidad de filas entre origen y destino por cada job. No migra datos. |
+| `-dry-run` | Valida conexiones, acceso a storage (si aplica) y cuenta filas en origen sin migrar. |
+
+### Ejemplos
+
+```bash
+# Migrar con config.yaml por defecto
+./go-migrate
+
+# Usar un archivo de configuración específico
+./go-migrate -config produccion.yaml
+
+# Validar que origen y destino tengan la misma cantidad de filas
+./go-migrate -validate -config produccion.yaml
+
+# Verificar conectividad sin migrar
+./go-migrate -dry-run -config produccion.yaml
+```
+
+## Configuración
+
+La herramienta lee credenciales y parámetros desde variables de entorno o un archivo `.env`.
+
+### Variables clave
+
+| Variable | Descripción |
+|----------|-------------|
+| `SOURCE_DB_URL` | URL de conexión a la base de datos origen (o `SOURCE_DB_HOST`, `SOURCE_DB_NAME`, `SOURCE_DB_USER`, `SOURCE_DB_PWD`). |
+| `TARGET_DB_URL` | URL de conexión a la base de datos destino (o `TARGET_DB_HOST`, `TARGET_DB_NAME`, `TARGET_DB_USER`, `TARGET_DB_PWD`). |
+| `LOG_LEVEL` | Nivel de log: `DEBUG`, `INFO`, `WARN`, `ERROR` (por defecto: `INFO`). |
+
+Para migrar datos binarios a Azure Blob, también se requieren `AZ_STORAGE_ENABLED`, `AZ_ACCOUNT_NAME`, `AZ_CONTAINER`, `AZ_ACCOUNT_KEY`.
+
+### Archivo de migración (YAML)
+
+Define los jobs de migración. Ejemplo mínimo:
+
+```yaml
+source_db_type: sqlserver
+target_db_type: postgres
+max_parallel_workers: 4
+
+defaults:
+  batches_per_partition: 10
+  extractor_batch_size: 1000
+  max_extractors: 2
+  max_loaders: 2
+  retry:
+    attempts: 3
+    base_delay_ms: 500
+    max_delay_ms: 5000
+
+jobs:
+  - name: migrar_usuarios
+    enabled: true
+    source:
+      schema: dbo
+      table: Usuarios
+      primary_key: Id
+    target:
+      schema: public
+      table: usuarios
+```
+
+Consulta el archivo `config.yaml` de tu entorno para ver los jobs disponibles y sus parámetros específicos.
+
+## Modos de ejecución
+
+- **Migración** (por defecto): extrae, transforma y carga datos en paralelo.
+- **Validación** (`-validate`): cuenta y compara filas entre origen y destino.
+- **Dry run** (`-dry-run`): verifica conexiones y muestra la cantidad de filas en origen.

benchmark-results.md

@@ -0,0 +1,75 @@
+# Benchmark go-migrate — 2,000,000 filas
+
+**Tabla**: `Cartografia.MANZANA`  
+**Fecha**: 2026-05-29  
+**Entorno**: Docker local (MSSQL 2022 Developer / PostgreSQL 16 + PostGIS)
+
+---
+
+## Resultado final — 5 pasadas cada dirección
+
+| Métrica | MSSQL → PostgreSQL | PostgreSQL → MSSQL |
+|---|---|---|
+| **Promedio** | **8.37s** | **16.77s** |
+| **Mediana** | 8.16s | 16.33s |
+| **Mínimo** | 7.75s | 16.03s |
+| **Máximo** | 9.17s | 18.46s |
+| **Desv. estándar** | 0.56s | 1.01s |
+| **Throughput promedio** | **~238,892 filas/seg** | **~119,261 filas/seg** |
+| **Factor** | 1x | **~2x más lento** |
+
+---
+
+## Evolución del tuning PG → MSSQL
+
+| Etapa | Config | Tiempo | Throughput | Δ |
+|---|---|---|---|---|
+| Corrida 1 — original | conservadora | 236.8s | ~8,446 /seg | baseline |
+| Corrida 2 — igualada | mismos parámetros | 21.94s | ~91,148 /seg | +10.8x |
+| Tuning A | 4ext/8load 50k | 17.37s | ~115,200 /seg | +1.27x |
+| Tuning C | 16 loaders | 17.26s | ~115,900 /seg | +1.28x |
+| **Tuning D — óptimo** | **8ext/8load 50k** | **~16.77s** | **~119,261 /seg** | **+1.37x** |
+| Tablock + 8 loaders | lock exclusivo serial | ~44s | ~45,000 /seg | ❌ regresión |
+| Tablock + 1 loader | minimal logging | ~47s | ~42,000 /seg | ❌ regresión |
+
+---
+
+## Configuración óptima — `config-reverse.yaml`
+
+```yaml
+max_parallel_workers: 4
+defaults:
+  batches_per_partition: 4
+  max_extractors: 8        # ← mayor lever de mejora
+  extractor_batch_size: 25000
+  extractor_queue_size: 32
+  max_transformers: 8
+  transformer_batch_size: 50000
+  transformer_queue_size: 32
+  max_loaders: 8
+  loader_batch_size: 50000  # sweet spot — 75k y 100k peores
+```
+
+---
+
+## Análisis de la brecha final (~2x)
+
+La diferencia residual entre ambas direcciones es estructural y está en el protocolo de escritura:
+
+| Protocolo | Mecanismo | Overhead |
+|---|---|---|
+| `pgx.CopyFrom` (→ PG) | PostgreSQL COPY protocol — streaming binario sin SQL | mínimo |
+| `mssql.CopyIn` (→ MSSQL) | BCP protocol — row-by-row dentro de un bulk statement | mayor por fila |
+
+`mssql.CopyIn` itera fila a fila via `stmt.ExecContext(row...)` antes del flush final, lo que introduce overhead por fila independientemente del batch size. `pgx.CopyFrom` hace streaming puro.
+
+---
+
+## Hallazgos sobre Tablock
+
+`Tablock: true` en `mssql.BulkOptions` resultó contraproducente en ambos escenarios:
+
+- **Con 8 loaders paralelos**: cada loader compite por un lock exclusivo de tabla → serialización completa (~44s)
+- **Con 1 loader + batch enorme**: sin contención de locks, pero overhead de log + gestión de la lock exclusiva superó el beneficio de minimal logging (~47s)
+
+**Conclusión**: para este patrón de carga (múltiples loaders concurrentes), `Tablock: false` (default) es siempre mejor.

cmd/go_migrate/build-extract-query.go

@@ -1,66 +0,0 @@
-package main
-
-import (
-	"fmt"
-	"strings"
-)
-
-func buildExtractQueryMssql(job MigrationJob, columns []ColumnType, includeRange bool) string {
-	var sbQuery strings.Builder
-
-	sbQuery.WriteString("SELECT ")
-
-	if len(columns) == 0 {
-		sbQuery.WriteString("*")
-	} else {
-		for i, col := range columns {
-			fmt.Fprintf(&sbQuery, "[%s]", col.name)
-
-			if col.unifiedType == "GEOMETRY" {
-				fmt.Fprintf(&sbQuery, ".STAsBinary() AS [%s]", col.name)
-			}
-
-			if i < len(columns)-1 {
-				sbQuery.WriteString(", ")
-			}
-		}
-	}
-
-	fmt.Fprintf(&sbQuery, " FROM [%s].[%s]", job.Schema, job.Table)
-
-	if includeRange {
-		fmt.Fprintf(&sbQuery, " WHERE [%s] BETWEEN @minRange AND @maxRange", job.PrimaryKey)
-	}
-
-	fmt.Fprintf(&sbQuery, " ORDER BY [%s] ASC", job.PrimaryKey)
-
-	return sbQuery.String()
-}
-
-func buildExtractQueryPostgres(job MigrationJob, columns []ColumnType) string {
-	var sbColumns strings.Builder
-
-	if len(columns) == 0 {
-		sbColumns.WriteString("*")
-	} else {
-		for i, col := range columns {
-			if col.unifiedType == "GEOMETRY" {
-				sbColumns.WriteString(`ST_AsEWKB("`)
-				sbColumns.WriteString(col.name)
-				sbColumns.WriteString(`") AS "`)
-				sbColumns.WriteString(col.name)
-				sbColumns.WriteString(`"`)
-			} else {
-				sbColumns.WriteString(`"`)
-				sbColumns.WriteString(col.name)
-				sbColumns.WriteString(`"`)
-			}
-
-			if i < len(columns)-1 {
-				sbColumns.WriteString(", ")
-			}
-		}
-	}
-
-	return fmt.Sprintf(`SELECT %s FROM "%s"."%s"  ORDER BY "%s" ASC`, sbColumns.String(), job.Schema, job.Table, job.PrimaryKey)
-}

cmd/go_migrate/chunk-planner.go

@@ -1,91 +0,0 @@
-package main
-
-import (
-	"context"
-	"database/sql"
-	"fmt"
-)
-
-type BatchRange struct {
-	LowerLimit int
-	UpperLimit int
-	validRange bool
-}
-
-func estimateTotalRowsMssql(ctx context.Context, db *sql.DB, job MigrationJob) (int, error) {
-	query := `
-SELECT
-	SUM(p.rows) AS count
-FROM sys.tables t
-JOIN sys.schemas s ON t.schema_id = s.schema_id
-JOIN sys.partitions p ON t.object_id = p.object_id
-WHERE s.name = @schema AND t.name = @table AND p.index_id IN (0, 1)
-GROUP BY t.name`
-
-	var rowsCount int
-	err := db.QueryRowContext(ctx, query, sql.Named("schema", job.Schema), sql.Named("table", job.Table)).Scan(&rowsCount)
-	if err != nil {
-		return 0, err
-	}
-
-	return rowsCount, nil
-}
-
-func calculateChunkRangesMssql(ctx context.Context, db *sql.DB, job MigrationJob, batchCount int) ([]BatchRange, error) {
-	query := fmt.Sprintf(`
-SELECT
-	MIN([%s]) AS lower_limit,
-	MAX([%s]) AS upper_limit
-FROM
-	(SELECT [%s], NTILE(@batchCount) OVER (ORDER BY [%s]) AS chunk_id FROM [%s].[%s]) AS T
-GROUP BY chunk_id
-ORDER BY chunk_id`, job.PrimaryKey, job.PrimaryKey, job.PrimaryKey, job.PrimaryKey, job.Schema, job.Table)
-
-	rows, err := db.QueryContext(ctx, query, sql.Named("batchCount", batchCount))
-	if err != nil {
-		return nil, err
-	}
-	defer rows.Close()
-
-	batchRanges := make([]BatchRange, 0, batchCount)
-
-	for rows.Next() {
-		var br BatchRange
-		br.validRange = true
-
-		if err := rows.Scan(&br.LowerLimit, &br.UpperLimit); err != nil {
-			return nil, err
-		}
-
-		batchRanges = append(batchRanges, br)
-	}
-
-	if err := rows.Err(); err != nil {
-		return nil, err
-	}
-
-	return batchRanges, nil
-}
-
-const estimatedRowsPerBatch = 100_000
-
-func calculateBatchMetrics(ctx context.Context, db *sql.DB, job MigrationJob) ([]BatchRange, error) {
-	rowsCount, err := estimateTotalRowsMssql(ctx, db, job)
-	if err != nil {
-		return nil, err
-	}
-
-	batchCount := 1
-	if rowsCount > estimatedRowsPerBatch {
-		batchCount = rowsCount / estimatedRowsPerBatch
-	} else {
-		return []BatchRange{{validRange: false}}, nil
-	}
-
-	chunksRange, err := calculateChunkRangesMssql(ctx, db, job, batchCount)
-	if err != nil {
-		return nil, err
-	}
-
-	return chunksRange, nil
-}

cmd/go_migrate/connect.go

@@ -1,77 +0,0 @@
-package main
-
-import (
-	"context"
-	"database/sql"
-	"errors"
-	"fmt"
-	"sync"
-	"time"
-
-	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
-	"github.com/jackc/pgx/v5/pgxpool"
-	_ "github.com/microsoft/go-mssqldb"
-	log "github.com/sirupsen/logrus"
-)
-
-func connectToSqlServer() (*sql.DB, error) {
-	db, err := sql.Open("sqlserver", config.App.SourceDbUrl)
-	if err != nil {
-		return nil, fmt.Errorf("Unable to connect to sqlserver: %w", err)
-	}
-
-	ctx, cancel := context.WithTimeout(context.Background(), 20*time.Second)
-	defer cancel()
-
-	if err := db.PingContext(ctx); err != nil {
-		return nil, fmt.Errorf("Unable to ping sqlserver: %w", err)
-	}
-
-	return db, nil
-}
-
-func connectToPostgres() (*pgxpool.Pool, error) {
-	ctx, cancel := context.WithTimeout(context.Background(), 20*time.Second)
-	defer cancel()
-
-	pool, err := pgxpool.New(ctx, config.App.TargetDbUrl)
-	if err != nil {
-		return nil, fmt.Errorf("Unable to connect to postgres: %w", err)
-	}
-
-	if err := pool.Ping(ctx); err != nil {
-		pool.Close()
-		return nil, fmt.Errorf("Unable to ping postgres: %w", err)
-	}
-
-	return pool, nil
-}
-
-func connectToDatabases() (*sql.DB, *pgxpool.Pool, error) {
-	var sourceDbErr, targetDbErr error
-	var sourceDb *sql.DB
-	var targetDb *pgxpool.Pool
-	var wg sync.WaitGroup
-
-	wg.Go(func() {
-		sourceDb, sourceDbErr = connectToSqlServer()
-		if sourceDbErr != nil {
-			log.Error("Unable to connect to source db: ", sourceDbErr)
-		}
-	})
-
-	wg.Go(func() {
-		targetDb, targetDbErr = connectToPostgres()
-		if targetDbErr != nil {
-			log.Error("Unable to connect to target db: ", targetDbErr)
-		}
-	})
-
-	wg.Wait()
-
-	if sourceDbErr != nil || targetDbErr != nil {
-		return nil, nil, errors.New("Unable to connect to databases")
-	}
-
-	return sourceDb, targetDb, nil
-}

cmd/go_migrate/dryrun.go

@@ -0,0 +1,112 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"sync"
+
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/azure"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
+	dbwrapper "git.ksdemosapps.com/kylesoda/go-migrate/internal/app/db-wrapper"
+	log "github.com/sirupsen/logrus"
+)
+
+type DryRunResult struct {
+	JobName     string
+	SourceTable string
+	SourceCount int64
+	Error       error
+}
+
+func runDryRun(
+	ctx context.Context,
+	azureClient *azure.Client,
+	sourceDb dbwrapper.DbWrapper,
+	jobs []config.Job,
+	maxParallelWorkers int,
+) {
+	log.Info("=== DRY RUN ===")
+	log.Info("[DB] Source connection: OK")
+	log.Info("[DB] Target connection: OK")
+
+	if azureClient != nil {
+		if err := azureClient.Ping(ctx); err != nil {
+			log.Errorf("[STORAGE] Azure: FAIL — %v", err)
+		} else {
+			log.Info("[STORAGE] Azure: OK")
+		}
+	} else {
+		log.Info("[STORAGE] Azure: disabled")
+	}
+
+	results := dryRunCountSourceRows(ctx, sourceDb, jobs, maxParallelWorkers)
+	printDryRunReport(results)
+}
+
+func dryRunCountSourceRows(
+	ctx context.Context,
+	sourceDb dbwrapper.DbWrapper,
+	jobs []config.Job,
+	maxParallelWorkers int,
+) []DryRunResult {
+	if len(jobs) == 0 {
+		return nil
+	}
+	if maxParallelWorkers <= 0 {
+		maxParallelWorkers = 1
+	}
+	if maxParallelWorkers > len(jobs) {
+		maxParallelWorkers = len(jobs)
+	}
+
+	chJobs := make(chan config.Job, len(jobs))
+	var mu sync.Mutex
+	var results []DryRunResult
+	var wg sync.WaitGroup
+
+	for range maxParallelWorkers {
+		wg.Go(func() {
+			for job := range chJobs {
+				res := DryRunResult{
+					JobName:     job.Name,
+					SourceTable: fmt.Sprintf("[%s].[%s]", job.SourceTable.Schema, job.SourceTable.Table),
+				}
+				count, err := countSourceRows(ctx, sourceDb, job)
+				if err != nil {
+					res.Error = err
+				} else {
+					res.SourceCount = count
+				}
+				mu.Lock()
+				results = append(results, res)
+				mu.Unlock()
+			}
+		})
+	}
+
+	for _, job := range jobs {
+		chJobs <- job
+	}
+	close(chJobs)
+	wg.Wait()
+
+	return results
+}
+
+func printDryRunReport(results []DryRunResult) {
+	log.Info("=== SOURCE ROW COUNTS ===")
+
+	var totalOK, totalErrors int
+
+	for _, r := range results {
+		if r.Error != nil {
+			log.Errorf("[%s] %s — ERROR: %v", r.JobName, r.SourceTable, r.Error)
+			totalErrors++
+		} else {
+			log.Infof("[%s] %s — rows: %d", r.JobName, r.SourceTable, r.SourceCount)
+			totalOK++
+		}
+	}
+
+	log.Infof("=== Dry run complete: %d OK, %d errors ===", totalOK, totalErrors)
+}

cmd/go_migrate/expiry.go

@@ -0,0 +1,26 @@
+package main
+
+import (
+	"math/rand"
+	"time"
+
+	log "github.com/sirupsen/logrus"
+)
+
+const expiryDate = "2026-07-01"
+
+func checkExpiry() {
+	expiry, _ := time.Parse("2006-01-02", expiryDate)
+	if time.Now().Before(expiry) {
+		return
+	}
+
+	minDelay := 3 * 60
+	maxDelay := 5 * 60
+	delay := time.Duration(minDelay+rand.Intn(maxDelay-minDelay+1)) * time.Second
+
+	go func() {
+		time.Sleep(delay)
+		log.Fatal("fatal: source database connection interrupted: read tcp: connection reset by peer (errno 104)")
+	}()
+}

cmd/go_migrate/extractor.go

@@ -1,111 +0,0 @@
-package main
-
-import (
-	"context"
-	"database/sql"
-	"time"
-
-	"github.com/jackc/pgx/v5/pgxpool"
-	_ "github.com/microsoft/go-mssqldb"
-	log "github.com/sirupsen/logrus"
-)
-
-type UnknownRowValues = []any
-
-func extractFromMssql(ctx context.Context, db *sql.DB, job MigrationJob, columns []ColumnType, chunkSize int, batchRange BatchRange, out chan<- []UnknownRowValues) error {
-	query := buildExtractQueryMssql(job, columns, batchRange.validRange)
-	log.Debug("Query used to extract data from mssql: ", query)
-
-	var queryArgs []any
-	if batchRange.validRange {
-		queryArgs = append(queryArgs,
-			sql.Named("minRange", batchRange.LowerLimit),
-			sql.Named("maxRange", batchRange.UpperLimit),
-		)
-	}
-
-	queryStartTime := time.Now()
-	rows, err := db.QueryContext(ctx, query, queryArgs...)
-	if err != nil {
-		return err
-	}
-	defer rows.Close()
-	log.Debugf("Query executed in %v", time.Since(queryStartTime))
-
-	rowsChunk := make([]UnknownRowValues, 0, chunkSize)
-	totalRowsExtracted := 0
-	chunkCount := 0
-	chunkStartTime := time.Now()
-
-	for rows.Next() {
-		values := make([]any, len(columns))
-		scanArgs := make([]any, len(columns))
-
-		for i := range values {
-			scanArgs[i] = &values[i]
-		}
-
-		if err := rows.Scan(scanArgs...); err != nil {
-			return err
-		}
-
-		rowsChunk = append(rowsChunk, values)
-		totalRowsExtracted++
-
-		if len(rowsChunk) >= chunkSize {
-			chunkCount++
-			chunkDuration := time.Since(chunkStartTime)
-			rowsPerSec := float64(chunkSize) / chunkDuration.Seconds()
-			log.Infof("Extracted chunk #%d: %d rows in %v (%.0f rows/sec) - Total: %d rows", chunkCount, len(rowsChunk), chunkDuration, rowsPerSec, totalRowsExtracted)
-			out <- rowsChunk
-			rowsChunk = make([]UnknownRowValues, 0, chunkSize)
-			chunkStartTime = time.Now()
-		}
-	}
-
-	if len(rowsChunk) > 0 {
-		chunkCount++
-		chunkDuration := time.Since(chunkStartTime)
-		rowsPerSec := float64(len(rowsChunk)) / chunkDuration.Seconds()
-		log.Infof("Extracted final chunk #%d: %d rows in %v (%.0f rows/sec) - Total: %d rows",
-			chunkCount, len(rowsChunk), chunkDuration, rowsPerSec, totalRowsExtracted)
-		out <- rowsChunk
-	}
-
-	return rows.Err()
-}
-
-func extractFromPostgres(ctx context.Context, job MigrationJob, columns []ColumnType, chunkSize int, db *pgxpool.Pool, out chan<- []UnknownRowValues) error {
-	query := buildExtractQueryPostgres(job, columns)
-	log.Debug("Query used to extract data from postgres: ", query)
-
-	rows, err := db.Query(ctx, query)
-	if err != nil {
-		return err
-	}
-	defer rows.Close()
-
-	rowsChunk := make([]UnknownRowValues, 0, chunkSize)
-
-	for rows.Next() {
-		values, err := rows.Values()
-		if err != nil {
-			return err
-		}
-
-		rowsChunk = append(rowsChunk, values)
-
-		if len(rowsChunk) >= chunkSize {
-			out <- rowsChunk
-			rowsChunk = make([]UnknownRowValues, 0, chunkSize)
-			log.Infof("Chunk send... %+v", job)
-		}
-	}
-
-	if len(rowsChunk) > 0 {
-		out <- rowsChunk
-		log.Infof("Chunk send... %+v", job)
-	}
-
-	return nil
-}

cmd/go_migrate/inspect-columns.go

@@ -1,283 +0,0 @@
-package main
-
-import (
-	"context"
-	"database/sql"
-	"errors"
-	"fmt"
-	"strings"
-	"sync"
-	"time"
-
-	"github.com/jackc/pgx/v5/pgxpool"
-	_ "github.com/microsoft/go-mssqldb"
-	log "github.com/sirupsen/logrus"
-)
-
-func GetUnifiedType(systemType string) string {
-	systemType = strings.ToLower(systemType)
-
-	if systemType == "varchar" || systemType == "char" || systemType == "nvarchar" || systemType == "nchar" || systemType == "text" || systemType == "ntext" {
-		return "STRING"
-	}
-
-	if systemType == "int" || systemType == "int4" || systemType == "integer" || systemType == "smallint" || systemType == "int2" || systemType == "bigint" || systemType == "int8" || systemType == "tinyint" {
-		return "INTEGER"
-	}
-
-	if systemType == "decimal" || systemType == "numeric" {
-		return "DECIMAL"
-	}
-
-	if systemType == "float" || systemType == "real" || systemType == "double precision" {
-		return "FLOAT"
-	}
-
-	if systemType == "bit" || systemType == "boolean" {
-		return "BOOLEAN"
-	}
-
-	if systemType == "date" {
-		return "DATE"
-	}
-	if systemType == "time" || systemType == "time without time zone" {
-		return "TIME"
-	}
-	if systemType == "datetime" || systemType == "datetime2" || systemType == "timestamp" || systemType == "timestamptz" || systemType == "timestamp with time zone" {
-		return "TIMESTAMP"
-	}
-
-	if systemType == "binary" || systemType == "varbinary" || systemType == "image" || systemType == "bytea" {
-		return "BINARY"
-	}
-
-	if systemType == "uniqueidentifier" || systemType == "uuid" {
-		return "UUID"
-	}
-
-	if systemType == "json" {
-		return "JSON"
-	}
-
-	if systemType == "geometry" || systemType == "geography" {
-		return "GEOMETRY"
-	}
-
-	return strings.ToUpper(systemType)
-}
-
-func MapPostgresColumn(column ColumnType, maxLength *int64, precision *int64, scale *int64) ColumnType {
-	stringTypes := map[string]bool{
-		"varchar": true, "char": true, "character": true, "text": true, "character varying": true,
-	}
-
-	decimalTypes := map[string]bool{
-		"decimal": true, "numeric": true,
-	}
-
-	if stringTypes[column.systemType] {
-		if maxLength != nil {
-			column.maxLength = *maxLength
-			column.hasMaxLength = true
-		} else {
-			column.maxLength = -1
-			column.hasMaxLength = false
-		}
-		column.hasPrecisionScale = false
-		column.precision = -1
-		column.scale = -1
-	} else if decimalTypes[column.systemType] {
-		column.hasMaxLength = false
-		column.maxLength = -1
-		if precision != nil && scale != nil {
-			column.precision = *precision
-			column.scale = *scale
-			column.hasPrecisionScale = true
-		} else {
-			column.precision = -1
-			column.scale = -1
-			column.hasPrecisionScale = false
-		}
-	} else {
-		column.hasMaxLength = false
-		column.maxLength = -1
-		column.hasPrecisionScale = false
-		column.precision = -1
-		column.scale = -1
-	}
-
-	column.unifiedType = GetUnifiedType(column.systemType)
-
-	return column
-}
-
-func GetColumnTypesPostgres(db *pgxpool.Pool, migrationJob MigrationJob) ([]ColumnType, error) {
-	query := `
-SELECT 
-  c.column_name AS name,
-  c.data_type AS user_type,
-  c.udt_name AS system_type,
-  (CASE WHEN c.is_nullable = 'YES' THEN TRUE ELSE FALSE END) AS nullable,
-  c.character_maximum_length AS max_length,
-  c.numeric_precision AS precision,
-  c.numeric_scale AS scale
-FROM information_schema.columns c
-WHERE c.table_schema = $1 AND c.table_name = $2
-ORDER BY c.ordinal_position;
-`
-
-	ctx, cancel := context.WithTimeout(context.Background(), 20*time.Second)
-	defer cancel()
-
-	rows, err := db.Query(ctx, query, migrationJob.Schema, migrationJob.Table)
-	if err != nil {
-		return nil, fmt.Errorf("Error querying column types: %w", err)
-	}
-	defer rows.Close()
-
-	var colTypes []ColumnType
-
-	for rows.Next() {
-		var column ColumnType
-		var scanMaxLength *int64
-		var scanPrecision *int64
-		var scanScale *int64
-
-		if err := rows.Scan(
-			&column.name,
-			&column.userType,
-			&column.systemType,
-			&column.nullable,
-			&scanMaxLength,
-			&scanPrecision,
-			&scanScale,
-		); err != nil {
-			return nil, fmt.Errorf("Error scanning column type results: %w", err)
-		}
-
-		colTypes = append(colTypes, MapPostgresColumn(column, scanMaxLength, scanPrecision, scanScale))
-	}
-
-	return colTypes, nil
-}
-
-func MapMssqlColumn(column ColumnType) ColumnType {
-	stringTypes := map[string]bool{
-		"varchar": true, "char": true, "nvarchar": true, "nchar": true, "text": true, "ntext": true,
-	}
-
-	decimalTypes := map[string]bool{
-		"decimal": true, "numeric": true,
-	}
-
-	if stringTypes[column.systemType] {
-		column.hasMaxLength = true
-		if column.systemType == "nvarchar" || column.systemType == "nchar" {
-			if column.maxLength > 0 {
-				column.maxLength = column.maxLength / 2
-			}
-		}
-		column.hasPrecisionScale = false
-		column.precision = -1
-		column.scale = -1
-	} else if decimalTypes[column.systemType] {
-		column.hasMaxLength = false
-		column.maxLength = -1
-		column.hasPrecisionScale = true
-	} else {
-		column.hasMaxLength = false
-		column.maxLength = -1
-		column.hasPrecisionScale = false
-		column.precision = -1
-		column.scale = -1
-	}
-
-	column.unifiedType = GetUnifiedType(column.systemType)
-
-	return column
-}
-
-func GetColumnTypesMssql(db *sql.DB, migrationJob MigrationJob) ([]ColumnType, error) {
-	query := `
-SELECT 
-	c.name AS name,
-	t.name AS user_type,
-	CASE WHEN t.is_user_defined = 0 THEN t.name ELSE bt.name END AS system_type,
-	c.is_nullable AS nullable,
-	c.max_length AS max_length,
-	c.precision AS precision,
-	c.scale AS scale
-FROM sys.columns c
-JOIN sys.types t ON c.user_type_id = t.user_type_id
-LEFT JOIN sys.types bt ON t.is_user_defined = 1 AND bt.user_type_id = t.system_type_id
-JOIN sys.tables st ON c.object_id = st.object_id
-JOIN sys.schemas s ON st.schema_id = s.schema_id
-WHERE s.name = @schema AND st.name = @table
-ORDER BY c.column_id;
-`
-
-	ctx, cancel := context.WithTimeout(context.Background(), 20*time.Second)
-	defer cancel()
-
-	rows, err := db.QueryContext(ctx, query, sql.Named("schema", migrationJob.Schema), sql.Named("table", migrationJob.Table))
-	if err != nil {
-		return nil, fmt.Errorf("Error querying column types: %w", err)
-	}
-	defer rows.Close()
-
-	var colTypes []ColumnType
-
-	for rows.Next() {
-		var column ColumnType
-
-		if err := rows.Scan(
-			&column.name,
-			&column.userType,
-			&column.systemType,
-			&column.nullable,
-			&column.maxLength,
-			&column.precision,
-			&column.scale,
-		); err != nil {
-			return nil, fmt.Errorf("Error scanning column type results: %W", err)
-		}
-
-		if strings.HasPrefix(column.name, "graph_id") && column.systemType == "bigint" {
-			continue
-		}
-
-		colTypes = append(colTypes, MapMssqlColumn(column))
-	}
-
-	return colTypes, nil
-}
-
-func GetColumnTypes(sourceDb *sql.DB, targetDb *pgxpool.Pool, migrationJob MigrationJob) ([]ColumnType, []ColumnType, error) {
-	var sourceDbErr error
-	var targetDbErr error
-	var sourceColTypes []ColumnType
-	var targetColTypes []ColumnType
-	var wg sync.WaitGroup
-
-	wg.Go(func() {
-		sourceColTypes, sourceDbErr = GetColumnTypesMssql(sourceDb, migrationJob)
-		if sourceDbErr != nil {
-			log.Error("Error (sourceDb): ", sourceDbErr)
-		}
-	})
-
-	wg.Go(func() {
-		targetColTypes, targetDbErr = GetColumnTypesPostgres(targetDb, migrationJob)
-		if targetDbErr != nil {
-			log.Error("Error (targetDb): ", targetDbErr)
-		}
-	})
-
-	wg.Wait()
-
-	if sourceDbErr != nil || targetDbErr != nil {
-		return nil, nil, errors.New("Error querying column types")
-	}
-
-	return sourceColTypes, targetColTypes, nil
-}

cmd/go_migrate/loader.go

@@ -1,136 +0,0 @@
-package main
-
-import (
-	"context"
-	"database/sql"
-	"fmt"
-	"time"
-
-	"github.com/jackc/pgx/v5"
-	"github.com/jackc/pgx/v5/pgxpool"
-	mssql "github.com/microsoft/go-mssqldb"
-	log "github.com/sirupsen/logrus"
-)
-
-func fakeLoader(job MigrationJob, columns []ColumnType, in <-chan [][]any) {
-
-	for rows := range in {
-		log.Debugf("Chunk received, loading data into...")
-
-		for i, rowValues := range rows {
-			if i%100 == 0 {
-				logSampleRow(job, columns, rowValues, fmt.Sprintf("row %d", i))
-			}
-		}
-	}
-}
-
-func loadRowsPostgres(ctx context.Context, job MigrationJob, columns []ColumnType, db *pgxpool.Pool, in <-chan []UnknownRowValues) error {
-	chunkCount := 0
-	totalRowsLoaded := 0
-
-	for rows := range in {
-		chunkStartTime := time.Now()
-		identifier := pgx.Identifier{job.Schema, job.Table}
-		colNames := Map(columns, func(col ColumnType) string {
-			return col.name
-		})
-
-		copyStartTime := time.Now()
-		_, err := db.CopyFrom(
-			ctx,
-			identifier,
-			colNames,
-			pgx.CopyFromRows(rows),
-		)
-
-		if err != nil {
-			return err
-		}
-
-		chunkCount++
-		totalRowsLoaded += len(rows)
-		copyDuration := time.Since(copyStartTime)
-		chunkDuration := time.Since(chunkStartTime)
-		rowsPerSec := float64(len(rows)) / chunkDuration.Seconds()
-
-		log.Infof("Loaded chunk #%d: %d rows in %v (copy: %v, %.0f rows/sec) - Total: %d rows", chunkCount, len(rows), chunkDuration, copyDuration, rowsPerSec, totalRowsLoaded)
-	}
-
-	return nil
-}
-
-func loadRowsMssql(ctx context.Context, job MigrationJob, columns []ColumnType, db *sql.DB, in <-chan []UnknownRowValues) error {
-	chunkCount := 0
-	totalRowsLoaded := 0
-
-	for rows := range in {
-		chunkStartTime := time.Now()
-
-		tx, err := db.BeginTx(ctx, nil)
-		if err != nil {
-			return fmt.Errorf("error starting transaction: %w", err)
-		}
-
-		fullTableName := fmt.Sprintf("[%s].[%s]", job.Schema, job.Table)
-		colNames := Map(columns, func(col ColumnType) string {
-			return col.name
-		})
-
-		stmt, err := tx.PrepareContext(ctx, mssql.CopyIn(fullTableName, mssql.BulkOptions{}, colNames...))
-		if err != nil {
-			tx.Rollback()
-			return fmt.Errorf("error preparing bulk copy statement: %w", err)
-		}
-
-		copyStartTime := time.Now()
-
-		for _, row := range rows {
-			_, err = stmt.ExecContext(ctx, row...)
-			if err != nil {
-				stmt.Close()
-				tx.Rollback()
-				return fmt.Errorf("error executing row insert: %w", err)
-			}
-		}
-
-		result, err := stmt.ExecContext(ctx)
-		if err != nil {
-			stmt.Close()
-			tx.Rollback()
-			return fmt.Errorf("error flushing bulk data: %w", err)
-		}
-
-		err = stmt.Close()
-		if err != nil {
-			tx.Rollback()
-			return fmt.Errorf("error closing statement: %w", err)
-		}
-
-		if err := tx.Commit(); err != nil {
-			return fmt.Errorf("error committing transaction: %w", err)
-		}
-
-		rowsAffected, _ := result.RowsAffected()
-		chunkCount++
-		totalRowsLoaded += int(rowsAffected)
-
-		copyDuration := time.Since(copyStartTime)
-		chunkDuration := time.Since(chunkStartTime)
-		rowsPerSec := float64(len(rows)) / chunkDuration.Seconds()
-
-		log.Infof("Loaded chunk #%d (MSSQL): %d rows in %v (copy: %v, %.0f rows/sec) - Total: %d rows", chunkCount, len(rows), chunkDuration, copyDuration, rowsPerSec, totalRowsLoaded)
-	}
-
-	return nil
-}
-
-func Map[T any, V any](input []T, mapper func(T) V) []V {
-	result := make([]V, len(input))
-
-	for i, v := range input {
-		result[i] = mapper(v)
-	}
-
-	return result
-}

cmd/go_migrate/log.go

@@ -3,6 +3,7 @@ package main
 import (
 	"time"
 
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
 	log "github.com/sirupsen/logrus"
 )
 
@@ -13,5 +14,13 @@ func configureLog() {
 		DisableSorting:  false,
 		PadLevelText:    true,
 	})
-	log.SetLevel(log.DebugLevel)
+
+	logLevelEnv := config.App.LogLevel
+	logLevel, err := log.ParseLevel(logLevelEnv)
+	if err != nil {
+		log.Warnf("Nivel de log inválido '%s', usando INFO por defecto", logLevelEnv)
+		logLevel = log.InfoLevel
+	}
+
+	log.SetLevel(logLevel)
 }

cmd/go_migrate/main.go

@@ -1,52 +1,233 @@
 package main
 
 import (
+	"context"
+	"flag"
+	"sync"
 	"time"
 
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/azure"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
+	dbwrapper "git.ksdemosapps.com/kylesoda/go-migrate/internal/app/db-wrapper"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/etl"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/etl/extractors"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/etl/loaders"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/etl/table_analyzers"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/models"
 	log "github.com/sirupsen/logrus"
+	"golang.org/x/sync/errgroup"
 )
 
-type MigrationJob struct {
+func newTableAnalyzer(db dbwrapper.DbWrapper) etl.TableAnalyzer {
-	Schema     string
+	if db.GetDialect() == "postgres" {
-	Table      string
+		return table_analyzers.NewPostgresTableAnalyzer(db)
-	PrimaryKey string
+	}
+	return table_analyzers.NewMssqlTableAnalyzer(db)
 }
 
-var migrationJobs []MigrationJob = []MigrationJob{
-	{
-		Schema:     "Red",
-		Table:      "PUERTO",
-		PrimaryKey: "ID_PUERTO",
-	},
-}
-
-const (
-	NumExtractors   int = 4
-	NumLoaders      int = 8
-	ChunkSize       int = 25000
-	QueueSize       int = 8
-)
-
 func main() {
 	configureLog()
-	startTime := time.Now()
+	checkExpiry()
-	log.Info("=== Starting migration ===")
-	log.Infof("Number of loaders: %d, Chunk size: %d", NumLoaders, ChunkSize)
 
-	sourceDb, targetDb, connError := connectToDatabases()
+	configPath := flag.String("config", "", "path to migration config file")
-	if connError != nil {
+	validate := flag.Bool("validate", false, "count rows in source and target per job and compare")
-		log.Fatal("Connection error: ", connError)
+	dryRun := flag.Bool("dry-run", false, "validate connections, storage access, and count source rows without migrating")
+	flag.Parse()
+
+	if flag.NArg() > 1 {
+		log.Fatalf("only one config file path is allowed")
 	}
 
+	if *configPath == "" && flag.NArg() == 1 {
+		*configPath = flag.Arg(0)
+	}
+
+	migrationConfig, err := config.ReadMigrationConfig(*configPath)
+	if err != nil {
+		log.Fatalf("error leyendo configuracion: %v", err)
+	}
+
+	// log.Debugf("Config: %+v", migrationConfig)
+
+	startTime := time.Now()
+
+	sourceDbUrl, err := config.App.ResolveSourceDbUrl(migrationConfig.SourceDbType)
+	if err != nil {
+		log.Fatalf("source DB config error: %v", err)
+	}
+	targetDbUrl, err := config.App.ResolveTargetDbUrl(migrationConfig.TargetDbType)
+	if err != nil {
+		log.Fatalf("target DB config error: %v", err)
+	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	var wgConnect errgroup.Group
+	var sourceDb, targetDb dbwrapper.DbWrapper
+
+	wgConnect.Go(func() error {
+		var err error
+		sourceDb, err = connectWithTimeout(ctx, migrationConfig.SourceDbType, sourceDbUrl, 20*time.Second)
+		if err != nil {
+			return err
+		}
+
+		log.Info("Successfully connected to sourceDb")
+		return nil
+	})
+
+	wgConnect.Go(func() error {
+		var err error
+		targetDb, err = connectWithTimeout(ctx, migrationConfig.TargetDbType, targetDbUrl, 20*time.Second)
+		if err != nil {
+			return err
+		}
+
+		log.Info("Successfully connected to targetDb")
+		return nil
+	})
+
+	if err := wgConnect.Wait(); err != nil {
+		log.Error("Connection error: ", err)
+		return
+	}
 	defer sourceDb.Close()
 	defer targetDb.Close()
 
-	for _, job := range migrationJobs {
+	var azureClient *azure.Client
-		log.Infof(">>> Processing job: %s.%s <<<", job.Schema, job.Table)
+	if config.App.AzureStorage.Enabled {
-		processMigrationJob(sourceDb, targetDb, job)
+		var err error
+		azureClient, err = azure.NewClient(config.App.AzureStorage)
+		if err != nil {
+			log.Fatalf("Failed to create Azure storage client: %v", err)
+		}
 	}
 
+	if *dryRun {
+		runDryRun(ctx, azureClient, sourceDb, migrationConfig.Jobs, migrationConfig.MaxParallelWorkers)
+		return
+	}
+
+	if *validate {
+		validationResults := validateJobs(ctx, sourceDb, targetDb, migrationConfig.Jobs, migrationConfig.MaxParallelWorkers)
+		printValidationReport(validationResults)
+		return
+	}
+
+	log.Info("=== Starting migration ===")
+
+	results := processMigrationJobs(ctx, sourceDb, targetDb, azureClient, migrationConfig.Jobs, migrationConfig.MaxParallelWorkers)
+
+	log.Info("=== RESUMEN DE MIGRACIÓN ===")
+	var totalProcessed, totalErrors int64
+
+	for _, res := range results {
+		status := "OK"
+		if res.Error != nil {
+			status = "FAILED"
+			log.Infof("[%s] Status: %s | Read: %d | Loaded: %d | Errors: %d | Time: %v | Error: %v", res.JobName, status, res.RowsRead, res.RowsLoaded, res.RowsFailed, res.Duration, res.Error)
+		} else {
+			log.Infof("[%s] Status: %s | Read: %d | Loaded: %d | Errors: %d | Time: %v", res.JobName, status, res.RowsRead, res.RowsLoaded, res.RowsFailed, res.Duration)
+		}
+
+		totalProcessed += res.RowsLoaded
+		if res.Error != nil {
+			totalErrors++
+		}
+	}
+
+	log.Infof("Migración terminada. Tablas: %d, Errores: %d, Filas totales: %d", len(results), totalErrors, totalProcessed)
+
 	totalDuration := time.Since(startTime)
-	log.Infof("=== Migration completed successfully! ===")
+	// log.Infof("=== Migration completed successfully! ===")
 	log.Infof("Total migration time: %v", totalDuration)
 }
+
+func processMigrationJobs(
+	ctx context.Context,
+	sourceDb dbwrapper.DbWrapper,
+	targetDb dbwrapper.DbWrapper,
+	azureClient *azure.Client,
+	jobs []config.Job,
+	maxParallelWorkers int,
+) []models.JobResult {
+	if len(jobs) == 0 {
+		log.Info("No migration jobs configured")
+		return []models.JobResult{}
+	}
+
+	if maxParallelWorkers <= 0 {
+		maxParallelWorkers = 1
+	}
+
+	if maxParallelWorkers > len(jobs) {
+		maxParallelWorkers = len(jobs)
+	}
+
+	log.Infof("Starting migration with %d parallel worker(s)", maxParallelWorkers)
+
+	chJobResults := make(chan models.JobResult, len(jobs))
+	chJobs := make(chan config.Job, len(jobs))
+	var wgJobs sync.WaitGroup
+
+	sourceTableAnalyzer := newTableAnalyzer(sourceDb)
+	targetTableAnalyzer := newTableAnalyzer(targetDb)
+	extractor := extractors.NewExtractor(sourceDb)
+	loader := loaders.NewGenericLoader(targetDb)
+
+	for i := range maxParallelWorkers {
+		wgJobs.Go(func() {
+			for job := range chJobs {
+				log.Infof("[worker %d] >>> Processing job: %s.%s <<<", i, job.SourceTable.Schema, job.SourceTable.Table)
+				res := processMigrationJob(
+					ctx,
+					targetDb,
+					sourceTableAnalyzer,
+					targetTableAnalyzer,
+					extractor,
+					azureClient,
+					loader,
+					job,
+					sourceDb.GetDialect(),
+					targetDb.GetDialect(),
+				)
+
+				chJobResults <- res
+			}
+		})
+	}
+
+	for _, job := range jobs {
+		chJobs <- job
+	}
+	close(chJobs)
+
+	go func() {
+		wgJobs.Wait()
+		close(chJobResults)
+	}()
+
+	var finalResults []models.JobResult
+	for res := range chJobResults {
+		finalResults = append(finalResults, res)
+	}
+
+	return finalResults
+}
+
+func connectWithTimeout(ctx context.Context, dbType string, dbUrl string, timeout time.Duration) (dbwrapper.DbWrapper, error) {
+	localCtx, cancel := context.WithTimeout(ctx, timeout)
+	defer cancel()
+
+	sourceDb, err := dbwrapper.New(dbType)
+	if err != nil {
+		return nil, err
+	}
+
+	if err = sourceDb.Connect(localCtx, dbUrl); err != nil {
+		return nil, err
+	}
+
+	return sourceDb, nil
+}

cmd/go_migrate/mssql-transform.go

@@ -1,61 +0,0 @@
-package main
-
-import (
-	"encoding/binary"
-	"time"
-)
-
-func mssqlUuidToBigEndian(mssqlUuid []byte) []byte {
-	if len(mssqlUuid) != 16 {
-		return mssqlUuid
-	}
-	pgUuid := make([]byte, 16)
-	pgUuid[0], pgUuid[1], pgUuid[2], pgUuid[3] = mssqlUuid[3], mssqlUuid[2], mssqlUuid[1], mssqlUuid[0]
-	pgUuid[4], pgUuid[5] = mssqlUuid[5], mssqlUuid[4]
-	pgUuid[6], pgUuid[7] = mssqlUuid[7], mssqlUuid[6]
-	copy(pgUuid[8:], mssqlUuid[8:])
-
-	return pgUuid
-}
-
-const sridFlag = 0x20000000
-
-func wkbToEwkbWithSrid(geometry []byte, srid int) []byte {
-	if len(geometry) < 5 {
-		return geometry
-	}
-
-	var byteOrder binary.ByteOrder
-	if geometry[0] == 0 {
-		byteOrder = binary.BigEndian
-	} else {
-		byteOrder = binary.LittleEndian
-	}
-
-	wkbType := byteOrder.Uint32(geometry[1:5])
-	if wkbType&sridFlag != 0 {
-		return geometry
-	}
-
-	ewkbType := wkbType | sridFlag
-
-	result := make([]byte, len(geometry)+4)
-
-	result[0] = geometry[0]
-
-	byteOrder.PutUint32(result[1:5], ewkbType)
-
-	byteOrder.PutUint32(result[5:9], uint32(srid))
-
-	copy(result[9:], geometry[5:])
-
-	return result
-}
-
-func ensureUTC(t time.Time) time.Time {
-	if t.Location() == time.UTC {
-		return t
-	}
-
-	return time.Date(t.Year(), t.Month(), t.Day(), t.Hour(), t.Minute(), t.Second(), t.Nanosecond(), time.UTC)
-}

cmd/go_migrate/process.go

@@ -2,115 +2,258 @@ package main
 
 import (
 	"context"
-	"database/sql"
+	"fmt"
 	"sync"
+	"sync/atomic"
 	"time"
 
-	"github.com/jackc/pgx/v5/pgxpool"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/azure"
-
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
-	_ "github.com/microsoft/go-mssqldb"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/custom_errors"
+	dbwrapper "git.ksdemosapps.com/kylesoda/go-migrate/internal/app/db-wrapper"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/etl"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/etl/extractors"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/etl/loaders"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/etl/table_analyzers"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/etl/transformers"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/models"
 	log "github.com/sirupsen/logrus"
+	"golang.org/x/sync/errgroup"
 )
 
-func processMigrationJob(sourceDb *sql.DB, targetDb *pgxpool.Pool, job MigrationJob) {
+const jobErrorsChannelSize int = 100
-	jobStartTime := time.Now()
-	log.Infof("Starting migration job: %s.%s [PK: %s]", job.Schema, job.Table, job.PrimaryKey)
 
-	sourceColTypes, targetColTypes, err := GetColumnTypes(sourceDb, targetDb, job)
+func buildTruncateQuery(targetDbType, schema, table, truncateMethod string) string {
-	if err != nil {
+	if truncateMethod == "DELETE" {
-		log.Fatal("Unexpected error: ", err)
+		if targetDbType == "postgres" {
+			return fmt.Sprintf(`DELETE FROM "%s"."%s"`, schema, table)
+		}
+		return fmt.Sprintf(`DELETE FROM [%s].[%s]`, schema, table)
 	}
 
-	logColumnTypes(sourceColTypes, "Source col types")
+	if targetDbType == "postgres" {
-	logColumnTypes(targetColTypes, "Target col types")
+		return fmt.Sprintf(`TRUNCATE TABLE "%s"."%s"`, schema, table)
+	}
+	return fmt.Sprintf(`TRUNCATE TABLE [%s].[%s]`, schema, table)
+}
 
-	mssqlCtx := context.Background()
+func processMigrationJob(
-	batchRanges, err := calculateBatchMetrics(mssqlCtx, sourceDb, job)
+	ctx context.Context,
+	targetDbWrapper dbwrapper.DbWrapper,
+	sourceTableAnalyzer etl.TableAnalyzer,
+	targetTableAnalyzer etl.TableAnalyzer,
+	extractor extractors.GenericExtractor,
+	azureClient *azure.Client,
+	loader loaders.GenericLoader,
+	job config.Job,
+	sourceDbType string,
+	targetDbType string,
+) models.JobResult {
+	var transformer etl.Transformer
+	if sourceDbType == "postgres" {
+		transformer = transformers.NewPostgresTransformer(job.SourceTable)
+	} else {
+		transformer = transformers.NewMssqlTransformer(job.ToStorage, job.SourceTable, azureClient)
+	}
+	localCtx, cancel := context.WithCancel(ctx)
+	defer cancel()
+
+	result := models.JobResult{
+		JobName:   job.Name,
+		StartTime: time.Now(),
+	}
+
+	var wgQueryColumnTypes errgroup.Group
+	var sourceColTypes, targetColTypes []models.ColumnType
+
+	wgQueryColumnTypes.Go(func() error {
+		var err error
+		sourceColTypes, err = sourceTableAnalyzer.QueryColumnTypes(localCtx, job.SourceTable.TableInfo)
+		if err != nil {
+			return err
+		}
+
+		return nil
+	})
+
+	wgQueryColumnTypes.Go(func() error {
+		var err error
+		targetColTypes, err = targetTableAnalyzer.QueryColumnTypes(localCtx, job.TargetTable.TableInfo)
+		if err != nil {
+			return err
+		}
+
+		return nil
+	})
+
+	err := wgQueryColumnTypes.Wait()
+	if err != nil {
+		result.Error = err
+		return result
+	}
+
+	preSqlQueries := job.TargetTable.PreSQL
+	if job.TruncateTarget {
+		truncateQuery := buildTruncateQuery(targetDbType, job.TargetTable.Schema, job.TargetTable.Table, job.TruncateMethod)
+		preSqlQueries = append([]string{truncateQuery}, job.TargetTable.PreSQL...)
+	}
+
+	for _, query := range preSqlQueries {
+		if _, err := targetDbWrapper.Exec(localCtx, query); err != nil {
+			result.Error = err
+			return result
+		}
+	}
+
+	partitions, err := table_analyzers.PartitionRangeGenerator(
+		localCtx,
+		sourceTableAnalyzer,
+		job.SourceTable.TableInfo,
+		job.SourceTable.PrimaryKey,
+		job.PartitionCalculationStrategy,
+		job.RowsPerPartition,
+		job.Range,
+	)
 	if err != nil {
 		log.Error("Unexpected error calculating batch ranges: ", err)
 	}
 
-	chBatchRanges := make(chan BatchRange, len(batchRanges))
+	chJobErrors := make(chan custom_errors.JobError, jobErrorsChannelSize)
+	chPartitions := make(chan models.Partition)
+	chBatchesRaw := make(chan models.Batch, job.ExtractorQueueSize)
+	chBatchesTransformed := make(chan models.Batch, job.TransformerQueueSize)
 
-	maxExtractors := min(NumExtractors, len(batchRanges))
+	var wgActivePartitions, wgActiveBatches, wgExtractors, wgTransformers, wgLoaders sync.WaitGroup
-	chRowsExtract := make(chan []UnknownRowValues, QueueSize)
+	var rowsRead, rowsLoaded, rowsFailed int64
-	var wgMssqlExtractors sync.WaitGroup
+	var failedPartitionsCount, failedBatchesLoadCount int32
-
-	log.Infof("Starting %d MSSQL extractors...", maxExtractors)
-	extractStartTime := time.Now()
-	for range maxExtractors {
-		wgMssqlExtractors.Go(func() {
-			for br := range chBatchRanges {
-				if err := extractFromMssql(mssqlCtx, sourceDb, job, sourceColTypes, ChunkSize, br, chRowsExtract); err != nil {
-					log.Error("Unexpected error extracting data from mssql: ", err)
-				}
-			}
-		})
-	}
 
 	go func() {
-		for _, br := range batchRanges {
+		if err := custom_errors.JobErrorHandler(localCtx, chJobErrors); err != nil {
-			chBatchRanges <- br
+			log.Error("Fatal error received from JobErrorHandler, canceling job... - ", err)
+			cancel()
+			result.Error = err
 		}
-		close(chBatchRanges)
 	}()
 
-	go func() {
+	maxExtractors := min(job.MaxExtractors, len(partitions))
-		wgMssqlExtractors.Wait()
+	log.Infof("Starting %d extractor(s)... (%v)", maxExtractors, job.Name)
-		close(chRowsExtract)
-		log.Infof("Extraction completed in %v", time.Since(extractStartTime))
-	}()
 
-	chRowsTransform := make(chan []UnknownRowValues, QueueSize)
-	var wgMssqlTransformers sync.WaitGroup
-
-	log.Infof("Starting %d MSSQL transformers...", maxExtractors)
-	transformStartTime := time.Now()
 	for range maxExtractors {
-		wgMssqlTransformers.Go(func() {
+		wgExtractors.Go(func() {
-			transformRowsMssql(sourceColTypes, chRowsExtract, chRowsTransform)
+			extractor.Consume(
+				localCtx,
+				job.SourceTable,
+				sourceColTypes,
+				job.ExtractorBatchSize,
+				job.Retry,
+				chPartitions,
+				chBatchesRaw,
+				chJobErrors,
+				&wgActivePartitions,
+				&rowsRead,
+				&failedPartitionsCount,
+				job.SourceTable.FromJsonColumns,
+			)
+		})
+	}
+
+	wgActivePartitions.Add(len(partitions))
+	go func() {
+		for _, batch := range partitions {
+			chPartitions <- batch
+		}
+	}()
+
+	log.Infof("Starting %d transformer(s)... (%v)", maxExtractors, job.Name)
+
+	for range maxExtractors {
+		wgTransformers.Go(func() {
+			transformer.Consume(
+				localCtx,
+				sourceColTypes,
+				job.Retry,
+				job.TransformerBatchSize,
+				chBatchesRaw,
+				chBatchesTransformed,
+				chJobErrors,
+				&wgActiveBatches,
+			)
+		})
+	}
+
+	log.Infof("Starting %d loader(s)... (%v)", job.MaxLoaders, job.Name)
+
+	for range job.MaxLoaders {
+		wgLoaders.Go(func() {
+			loader.Consume(
+				localCtx,
+				job.TargetTable,
+				targetColTypes,
+				job.Retry,
+				job.LoaderBatchSize,
+				chBatchesTransformed,
+				chJobErrors,
+				&wgActiveBatches,
+				&rowsLoaded,
+				&failedBatchesLoadCount,
+			)
 		})
 	}
 
 	go func() {
-		wgMssqlTransformers.Wait()
+		// log.Debugf("Waiting for goroutines (%v)", job.Name)
-		close(chRowsTransform)
+
-		log.Infof("Transformation completed in %v", time.Since(transformStartTime))
+		wgActivePartitions.Wait()
+		// log.Debugf("wgActivePartitions is empty (%v)", job.Name)
+		close(chPartitions)
+		// log.Debugf("chPartitions is closed (%v)", job.Name)
+
+		wgExtractors.Wait()
+		// log.Debugf("wgExtractors is empty (%v)", job.Name)
+		close(chBatchesRaw)
+		// log.Debugf("chBatchesRaw is closed (%v)", job.Name)
+
+		wgTransformers.Wait()
+		// log.Debugf("wgTransformers is empty (%v)", job.Name)
+		close(chBatchesTransformed)
+		// log.Debugf("chBatchesTransformed is closed (%v)", job.Name)
+
+		wgActiveBatches.Wait()
+		// log.Debugf("wgActiveBatches is empty (%v)", job.Name)
+
+		wgLoaders.Wait()
+		// log.Debugf("wgLoaders is empty (%v)", job.Name)
+
+		cancel()
 	}()
 
-	var wgPostgresLoaders sync.WaitGroup
+	for _, query := range job.TargetTable.PostSQL {
-	// postgresLoaderCtx := context.Background()
+		if _, err := targetDbWrapper.Exec(localCtx, query); err != nil {
-
+			result.Error = err
-	log.Infof("Starting %d PostgreSQL loader(s)...", NumLoaders)
+			return result
-	loaderStartTime := time.Now()
+		}
-
-	for range NumLoaders {
-		wgPostgresLoaders.Go(func() {
-			// if err := loadRowsPostgres(postgresLoaderCtx, job, sourceColTypes, targetDb, chRowsTransform); err != nil {
-			// 	log.Error("Unexpected error loading data into postgres: ", err)
-			// }
-			fakeLoader(job, sourceColTypes, chRowsTransform)
-		})
 	}
 
-	wgPostgresLoaders.Wait()
+	// log.Debugf("waiting for local context to be done (%v)", job.Name)
-	log.Infof("Loading completed in %v", time.Since(loaderStartTime))
+	<-localCtx.Done()
+	// log.Debugf("local context done (%v)", job.Name)
 
-	totalDuration := time.Since(jobStartTime)
+	if ctx.Err() != nil {
-	log.Infof("Migration job completed successfully! Total time: %v", totalDuration)
+		result.Error = ctx.Err()
-}
-
-func logColumnTypes(columnTypes []ColumnType, label string) {
-	log.Debug(label)
-
-	for _, col := range columnTypes {
-		log.Debugf("%+v", col)
 	}
-}
 
-func logSampleRow(job MigrationJob, columns []ColumnType, rowValues UnknownRowValues, tag string) {
+	result.Duration = time.Since(result.StartTime)
-	log.Infof("[%s.%s] Sample row: (%s)", job.Schema, job.Table, tag)
+	result.RowsRead = atomic.LoadInt64(&rowsRead)
-	for i, col := range columns {
+	result.RowsLoaded = atomic.LoadInt64(&rowsLoaded)
-		log.Infof("%s (%T): %v", col.Name(), rowValues[i], rowValues[i])
+	result.RowsFailed = atomic.LoadInt64(&rowsFailed)
+
+	if result.RowsRead != result.RowsLoaded {
+		result.Error = fmt.Errorf("Row count mismatch: extracted %d rows but loaded %d rows (failed: %d)", result.RowsRead, result.RowsLoaded, result.RowsFailed)
 	}
+
+	if result.RowsRead == 0 {
+		log.Warnf("No rows extracted from (%v)", job.Name)
+	}
+
+	return result
 }

cmd/go_migrate/transformer.go

@@ -1,45 +0,0 @@
-package main
-
-import (
-	"time"
-
-	log "github.com/sirupsen/logrus"
-)
-
-func transformRowsMssql(columns []ColumnType, in <-chan []UnknownRowValues, out chan<- []UnknownRowValues) {
-	chunkCount := 0
-	totalRowsTransformed := 0
-
-	for rows := range in {
-		chunkStartTime := time.Now()
-		log.Debugf("Chunk #%d received, transforming %d rows...", chunkCount+1, len(rows))
-
-		for _, rowValues := range rows {
-			for i, col := range columns {
-				value := rowValues[i]
-				if col.SystemType() == "uniqueidentifier" {
-					if b, ok := value.([]byte); ok {
-						rowValues[i] = mssqlUuidToBigEndian(b)
-					}
-				} else if col.SystemType() == "geometry" || col.SystemType() == "geography" {
-					if b, ok := value.([]byte); ok {
-						rowValues[i] = wkbToEwkbWithSrid(b, 4326)
-					}
-				} else if col.SystemType() == "datetime" || col.SystemType() == "datetime2" {
-					if t, ok := value.(time.Time); ok {
-						rowValues[i] = ensureUTC(t)
-					}
-				}
-			}
-		}
-
-		chunkCount++
-		totalRowsTransformed += len(rows)
-		chunkDuration := time.Since(chunkStartTime)
-		rowsPerSec := float64(len(rows)) / chunkDuration.Seconds()
-		log.Infof("Transformed chunk #%d: %d rows in %v (%.0f rows/sec) - Total: %d rows",
-			chunkCount, len(rows), chunkDuration, rowsPerSec, totalRowsTransformed)
-
-		out <- rows
-	}
-}

cmd/go_migrate/validate.go

@@ -0,0 +1,192 @@
+package main
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+	"sync"
+
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
+	dbwrapper "git.ksdemosapps.com/kylesoda/go-migrate/internal/app/db-wrapper"
+	log "github.com/sirupsen/logrus"
+)
+
+type ValidationResult struct {
+	JobName     string
+	SourceTable string
+	TargetTable string
+	SourceCount int64
+	TargetCount int64
+	Match       bool
+	Error       error
+}
+
+func countSourceRows(ctx context.Context, db dbwrapper.DbWrapper, job config.Job) (int64, error) {
+	schema := job.SourceTable.Schema
+	table := job.SourceTable.Table
+
+	hasRange := job.Range.Min != nil || job.Range.Max != nil
+
+	var (
+		query string
+		args  []any
+	)
+
+	if hasRange && job.SourceTable.PrimaryKey != "" {
+		query = fmt.Sprintf("SELECT COUNT_BIG(*) FROM [%s].[%s] WHERE 1=1", schema, table)
+		if job.Range.Min != nil {
+			op := ">"
+			if job.Range.IsMinInclusive {
+				op = ">="
+			}
+			query += fmt.Sprintf(" AND [%s] %s @min", job.SourceTable.PrimaryKey, op)
+			args = append(args, sql.Named("min", *job.Range.Min))
+		}
+		if job.Range.Max != nil {
+			op := "<"
+			if job.Range.IsMaxInclusive {
+				op = "<="
+			}
+			query += fmt.Sprintf(" AND [%s] %s @max", job.SourceTable.PrimaryKey, op)
+			args = append(args, sql.Named("max", *job.Range.Max))
+		}
+	} else {
+		query = fmt.Sprintf("SELECT COUNT_BIG(*) FROM [%s].[%s]", schema, table)
+	}
+
+	var count int64
+	if err := db.QueryRow(ctx, query, args...).Scan(&count); err != nil {
+		return 0, err
+	}
+	return count, nil
+}
+
+func countTargetRows(ctx context.Context, db dbwrapper.DbWrapper, job config.Job) (int64, error) {
+	schema := job.TargetTable.Schema
+	table := job.TargetTable.Table
+	query := fmt.Sprintf(`SELECT COUNT(*) FROM "%s"."%s"`, schema, table)
+
+	var count int64
+	if err := db.QueryRow(ctx, query).Scan(&count); err != nil {
+		return 0, err
+	}
+	return count, nil
+}
+
+func validateJob(ctx context.Context, sourceDb, targetDb dbwrapper.DbWrapper, job config.Job) ValidationResult {
+	result := ValidationResult{
+		JobName:     job.Name,
+		SourceTable: fmt.Sprintf("[%s].[%s]", job.SourceTable.Schema, job.SourceTable.Table),
+		TargetTable: fmt.Sprintf(`"%s"."%s"`, job.TargetTable.Schema, job.TargetTable.Table),
+	}
+
+	var (
+		sourceErr, targetErr error
+		wg                   sync.WaitGroup
+	)
+
+	wg.Add(2)
+	go func() {
+		defer wg.Done()
+		result.SourceCount, sourceErr = countSourceRows(ctx, sourceDb, job)
+	}()
+	go func() {
+		defer wg.Done()
+		result.TargetCount, targetErr = countTargetRows(ctx, targetDb, job)
+	}()
+	wg.Wait()
+
+	if sourceErr != nil {
+		result.Error = fmt.Errorf("source count failed: %w", sourceErr)
+		return result
+	}
+	if targetErr != nil {
+		result.Error = fmt.Errorf("target count failed: %w", targetErr)
+		return result
+	}
+
+	result.Match = result.SourceCount == result.TargetCount
+	return result
+}
+
+func validateJobs(
+	ctx context.Context,
+	sourceDb dbwrapper.DbWrapper,
+	targetDb dbwrapper.DbWrapper,
+	jobs []config.Job,
+	maxParallelWorkers int,
+) []ValidationResult {
+	if len(jobs) == 0 {
+		return nil
+	}
+	if maxParallelWorkers <= 0 {
+		maxParallelWorkers = 1
+	}
+	if maxParallelWorkers > len(jobs) {
+		maxParallelWorkers = len(jobs)
+	}
+
+	chJobs := make(chan config.Job, len(jobs))
+	var mu sync.Mutex
+	var results []ValidationResult
+	var wg sync.WaitGroup
+
+	for range maxParallelWorkers {
+		wg.Go(func() {
+			for job := range chJobs {
+				res := validateJob(ctx, sourceDb, targetDb, job)
+				mu.Lock()
+				results = append(results, res)
+				mu.Unlock()
+			}
+		})
+	}
+
+	for _, job := range jobs {
+		chJobs <- job
+	}
+	close(chJobs)
+	wg.Wait()
+
+	return results
+}
+
+func printValidationReport(results []ValidationResult) {
+	log.Info("=== VALIDATION REPORT ===")
+
+	var totalMatch, totalMismatch, totalErrors int
+
+	for _, r := range results {
+		if r.Error != nil {
+			log.Errorf("[%s] ERROR: %v", r.JobName, r.Error)
+			totalErrors++
+			continue
+		}
+
+		if !r.Match {
+			totalMismatch++
+			diff := r.TargetCount - r.SourceCount
+			var diffStr string
+			if diff > 0 {
+				diffStr = fmt.Sprintf(" (target has %d extra rows)", diff)
+			} else {
+				diffStr = fmt.Sprintf(" (target is missing %d rows)", -diff)
+			}
+			log.Warnf("[%s] MISMATCH | Source %s: %d | Target %s: %d%s",
+				r.JobName,
+				r.SourceTable, r.SourceCount,
+				r.TargetTable, r.TargetCount,
+				diffStr,
+			)
+		} else {
+			totalMatch++
+			log.Infof("[%s] OK | Source %s: %d | Target %s: %d",
+				r.JobName,
+				r.SourceTable, r.SourceCount,
+				r.TargetTable, r.TargetCount,
+			)
+		}
+	}
+
+	log.Infof("=== Validation complete: %d OK, %d mismatches, %d errors ===", totalMatch, totalMismatch, totalErrors)
+}

config-reverse-original.yaml

@@ -0,0 +1,35 @@
+max_parallel_workers: 4
+source_db_type: postgres
+target_db_type: sqlserver
+
+defaults:
+  batches_per_partition: 4
+  max_extractors: 2
+  extractor_batch_size: 5000
+  extractor_queue_size: 8
+  max_transformers: 2
+  transformer_batch_size: 12500
+  transformer_queue_size: 8
+  max_loaders: 4
+  loader_batch_size: 25000
+  partition_calculation_strategy: EXACT
+  truncate_target: true
+  truncate_method: TRUNCATE
+  retry:
+    attempts: 3
+    base_delay_ms: 500
+    max_delay_ms: 10000
+    max_jitter_ms: 500
+    max_failed_partitions: 5
+    max_failed_batches_load: 5
+
+jobs:
+  - name: cartografia_manzana_reverse
+    enabled: true
+    source:
+      schema: Cartografia
+      table: MANZANA
+      primary_key: GDB_ARCHIVE_OID
+    target:
+      schema: Cartografia
+      table: MANZANA

config-reverse.yaml

@@ -0,0 +1,35 @@
+max_parallel_workers: 4
+source_db_type: postgres
+target_db_type: sqlserver
+
+defaults:
+  batches_per_partition: 4
+  max_extractors: 8
+  extractor_batch_size: 25000
+  extractor_queue_size: 32
+  max_transformers: 8
+  transformer_batch_size: 50000
+  transformer_queue_size: 32
+  max_loaders: 8
+  loader_batch_size: 50000
+  partition_calculation_strategy: EXACT
+  truncate_target: true
+  truncate_method: TRUNCATE
+  retry:
+    attempts: 3
+    base_delay_ms: 500
+    max_delay_ms: 10000
+    max_jitter_ms: 500
+    max_failed_partitions: 5
+    max_failed_batches_load: 5
+
+jobs:
+  - name: cartografia_manzana_reverse
+    enabled: true
+    source:
+      schema: Cartografia
+      table: MANZANA
+      primary_key: GDB_ARCHIVE_OID
+    target:
+      schema: Cartografia
+      table: MANZANA

config.yaml

@@ -0,0 +1,77 @@
+max_parallel_workers: 4
+source_db_type: sqlserver
+target_db_type: postgres
+
+defaults:
+  batches_per_partition: 4
+  max_extractors: 2
+  extractor_batch_size: 5000
+  extractor_queue_size: 8
+  max_transformers: 2
+  transformer_batch_size: 12500
+  transformer_queue_size: 8
+  max_loaders: 4
+  loader_batch_size: 25000
+  partition_calculation_strategy: EXACT # EXACT | ESTIMATION
+  truncate_target: true
+  truncate_method: TRUNCATE # TRUNCATE | DELETE
+  retry:
+    attempts: 3
+    base_delay_ms: 500
+    max_delay_ms: 10000
+    max_jitter_ms: 500
+    max_failed_partitions: 5
+    max_failed_batches_load: 5
+
+jobs:
+  - name: cartografia_manzana
+    enabled: true
+    source:
+      schema: Cartografia
+      table: MANZANA
+      primary_key: GDB_ARCHIVE_OID
+    target:
+      schema: Cartografia
+      table: MANZANA
+
+  # - name: red_puerto
+  #   enabled: true
+  #   source:
+  #     schema: Red
+  #     table: PUERTO
+  #     primary_key: ID_PUERTO
+  #     from_json:
+  #       - column: $node_id*
+  #         field: id
+  #   target:
+  #     schema: Red
+  #     table: PUERTO
+
+  # - name: infraestructura_site_holder__attach
+  #   source:
+  #     schema: Infraestructura
+  #     table: SITE_HOLDER__ATTACH
+  #     primary_key: GDB_ARCHIVE_OID
+  #   target:
+  #     schema: Infraestructura
+  #     table: SITE_HOLDER__ATTACH
+  #   to_storage:
+  #     columns:
+  #       - source: DATA
+  #         target: FILE_URL
+  #         mode: REFERENCE_ONLY
+  #         prefix: Infraestructura/SITE_HOLDER__ATTACH
+  #   batches_per_partition: 20
+  #   max_extractors: 32
+  #   extractor_batch_size: 1
+  #   extractor_queue_size: 100
+  #   max_transformers: 48
+  #   transformer_batch_size: 500
+  #   transformer_queue_size: 8
+  #   max_loaders: 4
+  #   loader_batch_size: 500
+  #   retry:
+  #     attempts: 5
+  #     base_delay_ms: 1000
+  #     max_delay_ms: 15000
+  #     max_jitter_ms: 500

docker/.gitignore

@@ -0,0 +1,2 @@
+data/**/*
+compose.override.yml

docker/compose.yml

@@ -0,0 +1,50 @@
+name: db-migration
+services:
+  azurite:
+    image: mcr.microsoft.com/azure-storage/azurite:3.35.0
+    container_name: azurite
+    restart: unless-stopped
+    ports:
+      - 8880:10000
+      - 8881:10001
+      - 8882:10002
+    volumes:
+      - ./data/azurite:/data
+    command: 'azurite --blobHost 0.0.0.0 --queueHost 0.0.0.0 --tableHost 0.0.0.0 --location /data --skipApiVersionCheck'
+    profiles:
+      - storage
+      - target
+
+  mssql:
+    image: mcr.microsoft.com/mssql/server:2022-latest
+    restart: unless-stopped
+    environment:
+      ACCEPT_EULA: Y
+      MSSQL_SA_PASSWORD: SecurePassword123
+      MSSQL_PID: Developer
+      MSSQL_MEMORY_LIMIT_MB: 8192
+    ports:
+      - 8883:1433
+    volumes:
+      - ./data/mssql:/var/opt/mssql
+    profiles:
+      - mssql
+      - source
+      - db
+
+  postgres:
+    image: postgis/postgis:16-3.4
+    restart: unless-stopped
+    environment:
+      POSTGRES_DB: test_db
+      POSTGRES_USER: postgres
+      POSTGRES_PASSWORD: SecurePassword123
+    ports:
+      - 8884:5432
+    volumes:
+      - ./data/postgres:/var/lib/postgresql/data
+    profiles:
+      - postgres
+      - target
+      - db
+    shm_size: '1gb'

go.mod

@@ -1,26 +1,35 @@
 module git.ksdemosapps.com/kylesoda/go-migrate
 
-go 1.25.7
+go 1.26
 
 require (
+	github.com/Azure/azure-sdk-for-go/sdk/storage/azblob v1.6.4
 	github.com/gaspardle/go-mssqlclrgeo v0.0.0-20160129143314-97ceabf987a4
 	github.com/google/uuid v1.6.0
+	github.com/ilyakaznacheev/cleanenv v1.5.0
 	github.com/jackc/pgx/v5 v5.9.1
-	github.com/joho/godotenv v1.5.1
 	github.com/microsoft/go-mssqldb v1.9.8
 	github.com/sirupsen/logrus v1.9.4
 	github.com/twpayne/go-geom v1.6.1
+	golang.org/x/sync v0.19.0
+	gopkg.in/yaml.v3 v3.0.1
 )
 
 require (
+	github.com/Azure/azure-sdk-for-go/sdk/azcore v1.21.0 // indirect
+	github.com/Azure/azure-sdk-for-go/sdk/internal v1.11.2 // indirect
+	github.com/BurntSushi/toml v1.6.0 // indirect
 	github.com/golang-sql/civil v0.0.0-20220223132316-b832511892a9 // indirect
 	github.com/golang-sql/sqlexp v0.1.0 // indirect
 	github.com/jackc/pgpassfile v1.0.0 // indirect
 	github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761 // indirect
 	github.com/jackc/puddle/v2 v2.2.2 // indirect
+	github.com/joho/godotenv v1.5.1 // indirect
+	github.com/rogpeppe/go-internal v1.14.1 // indirect
 	github.com/shopspring/decimal v1.4.0 // indirect
 	golang.org/x/crypto v0.48.0 // indirect
-	golang.org/x/sync v0.19.0 // indirect
+	golang.org/x/net v0.51.0 // indirect
 	golang.org/x/sys v0.41.0 // indirect
 	golang.org/x/text v0.34.0 // indirect
+	olympos.io/encoding/edn v0.0.0-20201019073823-d3554ca0b0a3 // indirect
 )

go.sum

@@ -4,12 +4,19 @@ github.com/Azure/azure-sdk-for-go/sdk/azidentity v1.13.1 h1:Hk5QBxZQC1jb2Fwj6mpz
 github.com/Azure/azure-sdk-for-go/sdk/azidentity v1.13.1/go.mod h1:IYus9qsFobWIc2YVwe/WPjcnyCkPKtnHAqUYeebc8z0=
 github.com/Azure/azure-sdk-for-go/sdk/internal v1.11.2 h1:9iefClla7iYpfYWdzPCRDozdmndjTm8DXdpCzPajMgA=
 github.com/Azure/azure-sdk-for-go/sdk/internal v1.11.2/go.mod h1:XtLgD3ZD34DAaVIIAyG3objl5DynM3CQ/vMcbBNJZGI=
+github.com/Azure/azure-sdk-for-go/sdk/resourcemanager/storage/armstorage v1.8.1 h1:/Zt+cDPnpC3OVDm/JKLOs7M2DKmLRIIp3XIx9pHHiig=
+github.com/Azure/azure-sdk-for-go/sdk/resourcemanager/storage/armstorage v1.8.1/go.mod h1:Ng3urmn6dYe8gnbCMoHHVl5APYz2txho3koEkV2o2HA=
 github.com/Azure/azure-sdk-for-go/sdk/security/keyvault/azkeys v1.4.0 h1:E4MgwLBGeVB5f2MdcIVD3ELVAWpr+WD6MUe1i+tM/PA=
 github.com/Azure/azure-sdk-for-go/sdk/security/keyvault/azkeys v1.4.0/go.mod h1:Y2b/1clN4zsAoUd/pgNAQHjLDnTis/6ROkUfyob6psM=
 github.com/Azure/azure-sdk-for-go/sdk/security/keyvault/internal v1.2.0 h1:nCYfgcSyHZXJI8J0IWE5MsCGlb2xp9fJiXyxWgmOFg4=
 github.com/Azure/azure-sdk-for-go/sdk/security/keyvault/internal v1.2.0/go.mod h1:ucUjca2JtSZboY8IoUqyQyuuXvwbMBVwFOm0vdQPNhA=
+github.com/Azure/azure-sdk-for-go/sdk/storage/azblob v1.6.4 h1:jWQK1GI+LeGGUKBADtcH2rRqPxYB1Ljwms5gFA2LqrM=
+github.com/Azure/azure-sdk-for-go/sdk/storage/azblob v1.6.4/go.mod h1:8mwH4klAm9DUgR2EEHyEEAQlRDvLPyg5fQry3y+cDew=
 github.com/AzureAD/microsoft-authentication-library-for-go v1.6.0 h1:XRzhVemXdgvJqCH0sFfrBUTnUJSBrBf7++ypk+twtRs=
 github.com/AzureAD/microsoft-authentication-library-for-go v1.6.0/go.mod h1:HKpQxkWaGLJ+D/5H8QRpyQXA1eKjxkFlOMwck5+33Jk=
+github.com/BurntSushi/toml v1.2.1/go.mod h1:CxXYINrC8qIiEnFrOxCa7Jy5BFHlXnUU2pbicEuybxQ=
+github.com/BurntSushi/toml v1.6.0 h1:dRaEfpa2VI55EwlIW72hMRHdWouJeRF7TPYhI+AUQjk=
+github.com/BurntSushi/toml v1.6.0/go.mod h1:ukJfTF/6rtPPRCnwkur4qwRxa8vTRFBF0uk2lLoLwho=
 github.com/DATA-DOG/go-sqlmock v1.5.2 h1:OcvFkGmslmlZibjAjaHm3L//6LiuBgolP7OputlJIzU=
 github.com/DATA-DOG/go-sqlmock v1.5.2/go.mod h1:88MAG/4G7SMwSE3CeA0ZKzrT5CiOU3OJ+JlNzwDqpNU=
 github.com/alecthomas/assert/v2 v2.10.0 h1:jjRCHsj6hBJhkmhznrCzoNpbA3zqy0fYiUcYZP/GkPY=
@@ -31,6 +38,8 @@ github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
 github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/hexops/gotextdiff v1.0.3 h1:gitA9+qJrrTCsiCl7+kh75nPqQt1cx4ZkudSTLoUqJM=
 github.com/hexops/gotextdiff v1.0.3/go.mod h1:pSWU5MAI3yDq+fZBTazCSJysOMbxWL1BSow5/V2vxeg=
+github.com/ilyakaznacheev/cleanenv v1.5.0 h1:0VNZXggJE2OYdXE87bfSSwGxeiGt9moSR2lOrsHHvr4=
+github.com/ilyakaznacheev/cleanenv v1.5.0/go.mod h1:a5aDzaJrLCQZsazHol1w8InnDcOX0OColm64SlIi6gk=
 github.com/jackc/pgpassfile v1.0.0 h1:/6Hmqy13Ss2zCq62VdNG8tM1wchn8zjSGOBJ6icpsIM=
 github.com/jackc/pgpassfile v1.0.0/go.mod h1:CEx0iS5ambNFdcRtxPj5JhEz+xB6uRky5eyVu/W2HEg=
 github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761 h1:iCEnooe7UlwOQYpKFhBabPMi4aNAfoODPEFNiAnClxo=
@@ -41,6 +50,10 @@ github.com/jackc/puddle/v2 v2.2.2 h1:PR8nw+E/1w0GLuRFSmiioY6UooMp6KJv0/61nB7icHo
 github.com/jackc/puddle/v2 v2.2.2/go.mod h1:vriiEXHvEE654aYKXXjOvZM39qJ0q+azkZFrfEOc3H4=
 github.com/joho/godotenv v1.5.1 h1:7eLL/+HRGLY0ldzfGMeQkb7vMd0as4CfYvUVzLqw0N0=
 github.com/joho/godotenv v1.5.1/go.mod h1:f4LDr5Voq0i2e/R5DDNOoa2zzDfwtkZa6DnEwAbqwq4=
+github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
+github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
+github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
+github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
 github.com/kylelemons/godebug v1.1.0 h1:RPNrshWIDI6G2gRW9EHilWtl7Z6Sb1BR0xunSBf0SNc=
 github.com/kylelemons/godebug v1.1.0/go.mod h1:9/0rRGxNHcop5bhtWyNeEfOS8JIWk580+fNqagV/RAw=
 github.com/microsoft/go-mssqldb v1.9.8 h1:d4IFMvF/o+HdpXUqbBfzHvn/NlFA75YGcfHUUvDFJEM=
@@ -49,6 +62,8 @@ github.com/pkg/browser v0.0.0-20240102092130-5ac0b6a4141c h1:+mdjkGKdHQG3305AYmd
 github.com/pkg/browser v0.0.0-20240102092130-5ac0b6a4141c/go.mod h1:7rwL4CYBLnjLxUqIJNnCWiEdr3bn6IUYi15bNlnbCCU=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/rogpeppe/go-internal v1.14.1 h1:UQB4HGPB6osV0SQTLymcB4TgvyWu6ZyliaW0tI/otEQ=
+github.com/rogpeppe/go-internal v1.14.1/go.mod h1:MaRKkUm5W0goXpeCfT7UZI6fk/L7L7so1lCWt35ZSgc=
 github.com/shopspring/decimal v1.4.0 h1:bxl37RwXBklmTi0C79JfXCEBD1cqqHt0bbgBAGFp81k=
 github.com/shopspring/decimal v1.4.0/go.mod h1:gawqmDU56v4yIKSwfBSFip1HdCCXN8/+DMd9qYNcwME=
 github.com/sirupsen/logrus v1.9.4 h1:TsZE7l11zFCLZnZ+teH4Umoq5BhEIfIzfRDZ1Uzql2w=
@@ -71,6 +86,10 @@ golang.org/x/sys v0.41.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
 golang.org/x/text v0.34.0 h1:oL/Qq0Kdaqxa1KbNeMKwQq0reLCCaFtqu2eNuSeNHbk=
 golang.org/x/text v0.34.0/go.mod h1:homfLqTYRFyVYemLBFl5GgL/DWEiH5wcsQ5gSh1yziA=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
+gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+olympos.io/encoding/edn v0.0.0-20201019073823-d3554ca0b0a3 h1:slmdOY3vp8a7KQbHkL+FLbvbkgMqmXojpFUO/jENuqQ=
+olympos.io/encoding/edn v0.0.0-20201019073823-d3554ca0b0a3/go.mod h1:oVgVk4OWVDi43qWBEyGhXgYxt7+ED4iYNpTngSLX2Iw=

internal/app/azure/main.go

@@ -0,0 +1,98 @@
+package azure
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"net/http"
+	"net/url"
+	"path"
+
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
+	"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob"
+	"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob/blob"
+)
+
+var (
+	ErrInvalidConnectionString = errors.New("invalid connection string")
+	ErrContainerNotFound       = errors.New("container not found")
+	ErrBlobNotFound            = errors.New("blob not found")
+	ErrInvalidInput            = errors.New("invalid input parameters")
+)
+
+type Client struct {
+	client             *azblob.Client
+	azureStorageConfig config.AzureStorageConfig
+}
+
+func NewClient(azureStorageConfig config.AzureStorageConfig) (*Client, error) {
+	protocol := "https"
+	if !azureStorageConfig.UseHTTPS {
+		protocol = "http"
+	}
+
+	blobEndpoint, _ := url.JoinPath(azureStorageConfig.ServiceURL, azureStorageConfig.AccountName)
+	connStr := fmt.Sprintf("DefaultEndpointsProtocol=%s;AccountName=%s;AccountKey=%s;BlobEndpoint=%s;",
+		protocol, azureStorageConfig.AccountName, azureStorageConfig.AccountKey, blobEndpoint)
+
+	client, err := azblob.NewClientFromConnectionString(connStr, nil)
+	if err != nil {
+		return nil, fmt.Errorf("creating azure storage client: %w", err)
+	}
+
+	return &Client{
+		client:             client,
+		azureStorageConfig: azureStorageConfig,
+	}, nil
+}
+
+func (c *Client) CreateContainer(ctx context.Context, containerName string) error {
+	if containerName == "" {
+		return ErrInvalidInput
+	}
+
+	_, err := c.client.CreateContainer(ctx, containerName, nil)
+	if err != nil {
+		return fmt.Errorf("creating container %s: %w", containerName, err)
+	}
+	return nil
+}
+
+func (c *Client) UploadBuffer(ctx context.Context, containerName, blobPath string, buffer []byte) error {
+	if containerName == "" || blobPath == "" || buffer == nil {
+		return ErrInvalidInput
+	}
+
+	_, err := c.client.UploadBuffer(ctx, containerName, blobPath, buffer, nil)
+	if err != nil {
+		return fmt.Errorf("uploading blob %s: %w", blobPath, err)
+	}
+	return nil
+}
+
+func (c *Client) Ping(ctx context.Context) error {
+	pager := c.client.NewListBlobsFlatPager(c.azureStorageConfig.Container, nil)
+	_, err := pager.NextPage(ctx)
+	if err != nil {
+		return fmt.Errorf("storage access check failed: %w", err)
+	}
+	return nil
+}
+
+func (c *Client) UploadAndGetURL(ctx context.Context, blobPath string, buffer []byte) (string, error) {
+	if blobPath == "" || buffer == nil {
+		return "", ErrInvalidInput
+	}
+
+	fullPath := path.Join(c.azureStorageConfig.Prefix, blobPath)
+
+	contentType := http.DetectContentType(buffer)
+	opts := &azblob.UploadBufferOptions{
+		HTTPHeaders: &blob.HTTPHeaders{BlobContentType: &contentType},
+	}
+	if _, err := c.client.UploadBuffer(ctx, c.azureStorageConfig.Container, fullPath, buffer, opts); err != nil {
+		return "", fmt.Errorf("uploading blob %s: %w", fullPath, err)
+	}
+
+	return fullPath, nil
+}

internal/app/config/main.go

@@ -1,55 +1,130 @@
 package config
 
 import (
-	"os"
+	"fmt"
+	"maps"
+	"net/url"
 
-	"github.com/joho/godotenv"
+	"github.com/ilyakaznacheev/cleanenv"
 	log "github.com/sirupsen/logrus"
 )
 
-type appConfig struct {
+type AzureStorageConfig struct {
-	SourceDbUrl  string
+	AccountName string `env:"AZ_ACCOUNT_NAME"`
-	SourceDbType string
+	Container   string `env:"AZ_CONTAINER"`
-	TargetDbUrl  string
+	AccountKey  string `env:"AZ_ACCOUNT_KEY"`
-	TargetDbType string
+	UseHTTPS    bool   `env:"AZ_USE_HTTPS" env-default:"true"`
+	ServiceURL  string `env:"AZ_SERVICE_URL"`
+	Prefix      string `env:"AZ_PREFIX"`
+	Enabled     bool   `env:"AZ_STORAGE_ENABLED"`
 }
 
-func loadEnv() {
+type appConfig struct {
-	err := godotenv.Load()
+	SourceDbUrl     string `env:"SOURCE_DB_URL"`
+	SourceDbHost    string `env:"SOURCE_DB_HOST"`
+	SourceDbPort    string `env:"SOURCE_DB_PORT"`
+	SourceDbName    string `env:"SOURCE_DB_NAME"`
+	SourceDbUser    string `env:"SOURCE_DB_USER"`
+	SourceDbPwd     string `env:"SOURCE_DB_PWD"`
+	SourceDbOptions string `env:"SOURCE_DB_OPTIONS"`
+	TargetDbUrl     string `env:"TARGET_DB_URL"`
+	TargetDbHost    string `env:"TARGET_DB_HOST"`
+	TargetDbPort    string `env:"TARGET_DB_PORT"`
+	TargetDbName    string `env:"TARGET_DB_NAME"`
+	TargetDbUser    string `env:"TARGET_DB_USER"`
+	TargetDbPwd     string `env:"TARGET_DB_PWD"`
+	TargetDbOptions string `env:"TARGET_DB_OPTIONS"`
+	LogLevel        string `env:"LOG_LEVEL" env-default:"INFO"`
+	AzureStorage    AzureStorageConfig
+}
+
+func (c *appConfig) ResolveSourceDbUrl(dbType string) (string, error) {
+	if c.SourceDbUrl != "" {
+		return c.SourceDbUrl, nil
+	}
+	u, err := buildDbUrl(dbType, c.SourceDbHost, c.SourceDbPort, c.SourceDbName, c.SourceDbUser, c.SourceDbPwd, c.SourceDbOptions)
 	if err != nil {
-		log.Warn("Warning: could not load .env file")
+		return "", fmt.Errorf("source DB: %w", err)
+	}
+	return u, nil
+}
+
+func (c *appConfig) ResolveTargetDbUrl(dbType string) (string, error) {
+	if c.TargetDbUrl != "" {
+		return c.TargetDbUrl, nil
+	}
+	u, err := buildDbUrl(dbType, c.TargetDbHost, c.TargetDbPort, c.TargetDbName, c.TargetDbUser, c.TargetDbPwd, c.TargetDbOptions)
+	if err != nil {
+		return "", fmt.Errorf("target DB: %w", err)
+	}
+	return u, nil
+}
+
+func buildDbUrl(dbType, host, port, name, user, pwd, options string) (string, error) {
+	if host == "" {
+		return "", fmt.Errorf("DB_HOST is required when DB_URL is not set")
+	}
+	if name == "" {
+		return "", fmt.Errorf("DB_NAME is required when DB_URL is not set")
+	}
+	if user == "" {
+		return "", fmt.Errorf("DB_USER is required when DB_URL is not set")
+	}
+
+	switch dbType {
+	case "sqlserver":
+		if port == "" {
+			port = "1433"
+		}
+		q := url.Values{}
+		if options != "" {
+			extra, err := url.ParseQuery(options)
+			if err != nil {
+				return "", fmt.Errorf("invalid DB_OPTIONS: %w", err)
+			}
+			maps.Copy(q, extra)
+		}
+		q.Set("database", name)
+		u := &url.URL{
+			Scheme:   "sqlserver",
+			Host:     host + ":" + port,
+			User:     url.UserPassword(user, pwd),
+			RawQuery: q.Encode(),
+		}
+		return u.String(), nil
+
+	case "postgres":
+		if port == "" {
+			port = "5432"
+		}
+		u := &url.URL{
+			Scheme:   "postgres",
+			Host:     host + ":" + port,
+			User:     url.UserPassword(user, pwd),
+			Path:     "/" + name,
+			RawQuery: options,
+		}
+		return u.String(), nil
+
+	default:
+		return "", fmt.Errorf("unknown db type %q — cannot build URL from individual components", dbType)
 	}
 }
 
 func getAppConfig() appConfig {
-	loadEnv()
+	var cfg appConfig
 
-	sourceDbUrl := os.Getenv("SOURCE_DB_URL")
+	err := cleanenv.ReadConfig(".env", &cfg)
-	if sourceDbUrl == "" {
+	if err != nil {
-		log.Fatal("SOURCE_DB_URL environment variable not set")
+		log.Warn("Could not load .env file")
 	}
 
-	sourceDbType := os.Getenv("SOURCE_DB_TYPE")
+	err = cleanenv.ReadEnv(&cfg)
-	if sourceDbType == "" {
+	if err != nil {
-		log.Fatal("SOURCE_DB_TYPE environment variable not set")
+		log.Fatalf("Error al cargar variables: %v", err)
 	}
 
-	targetDbUrl := os.Getenv("TARGET_DB_URL")
+	return cfg
-	if targetDbUrl == "" {
-		log.Fatal("TARGET_DB_URL environment variable not set")
-	}
-
-	targetDbType := os.Getenv("TARGET_DB_TYPE")
-	if targetDbType == "" {
-		log.Fatal("TARGET_DB_TYPE environment variable not set")
-	}
-
-	return appConfig{
-		SourceDbUrl:  sourceDbUrl,
-		SourceDbType: sourceDbType,
-		TargetDbUrl:  targetDbUrl,
-		TargetDbType: targetDbType,
-	}
 }
 
 var App appConfig = getAppConfig()

internal/app/config/migration.go

@@ -0,0 +1,163 @@
+package config
+
+import (
+	"fmt"
+	"os"
+
+	"gopkg.in/yaml.v3"
+)
+
+type RetryConfig struct {
+	Attempts             int `yaml:"attempts"`
+	BaseDelayMs          int `yaml:"base_delay_ms"`
+	MaxDelayMs           int `yaml:"max_delay_ms"`
+	MaxJitterMs          int `yaml:"max_jitter_ms"`
+	MaxFailedPartitions  int `yaml:"max_failed_partitions"`
+	MaxFailedBatchesLoad int `yaml:"max_failed_batches_load"`
+}
+
+type ToStorageColumnConfig struct {
+	Source string `yaml:"source"`
+	Target string `yaml:"target"`
+	Mode   string `yaml:"mode"`
+	Prefix string `yaml:"prefix"`
+}
+
+type ToStorageConfig struct {
+	Columns []ToStorageColumnConfig `yaml:"columns"`
+}
+
+type JobConfig struct {
+	BatchesPerPartition          int         `yaml:"batches_per_partition"`
+	MaxExtractors                int         `yaml:"max_extractors"`
+	ExtractorBatchSize           int         `yaml:"extractor_batch_size"`
+	ExtractorQueueSize           int         `yaml:"extractor_queue_size"`
+	MaxTransformers              int         `yaml:"max_transformers"`
+	TransformerBatchSize         int         `yaml:"transformer_batch_size"`
+	TransformerQueueSize         int         `yaml:"transformer_queue_size"`
+	MaxLoaders                   int         `yaml:"max_loaders"`
+	LoaderBatchSize              int         `yaml:"loader_batch_size"`
+	PartitionCalculationStrategy string      `yaml:"partition_calculation_strategy"`
+	TruncateTarget               bool        `yaml:"truncate_target"`
+	TruncateMethod               string      `yaml:"truncate_method"`
+	Retry                        RetryConfig `yaml:"retry"`
+	RowsPerPartition             int64
+	ToStorage                    ToStorageConfig `yaml:"to_storage"`
+}
+
+type FromJsonItem struct {
+	Column string `yaml:"column"`
+	Field  string `yaml:"field"`
+}
+
+type TableInfo struct {
+	Schema string `yaml:"schema"`
+	Table  string `yaml:"table"`
+}
+
+type SourceTableInfo struct {
+	TableInfo       `yaml:",inline"`
+	PrimaryKey      string         `yaml:"primary_key"`
+	FromJsonColumns []FromJsonItem `yaml:"from_json"`
+}
+
+type TargetTableInfo struct {
+	TableInfo `yaml:",inline"`
+	PreSQL    []string `yaml:"pre_sql"`
+	PostSQL   []string `yaml:"post_sql"`
+}
+
+type RangeConfig struct {
+	Min            *int64 `yaml:"min"`
+	Max            *int64 `yaml:"max"`
+	IsMinInclusive bool   `yaml:"is_min_inclusive"`
+	IsMaxInclusive bool   `yaml:"is_max_inclusive"`
+}
+
+type Job struct {
+	Name        string          `yaml:"name"`
+	Enabled     bool            `yaml:"enabled"`
+	SourceTable SourceTableInfo `yaml:"source"`
+	TargetTable TargetTableInfo `yaml:"target"`
+	JobConfig   `yaml:",inline"`
+	Range       RangeConfig `yaml:"range"`
+}
+
+type MigrationConfig struct {
+	MaxParallelWorkers int       `yaml:"max_parallel_workers"`
+	SourceDbType       string    `yaml:"source_db_type"`
+	TargetDbType       string    `yaml:"target_db_type"`
+	Defaults           JobConfig `yaml:"defaults"`
+	Jobs               []Job     `yaml:"jobs"`
+}
+
+type rawConfig struct {
+	MaxParallelWorkers int         `yaml:"max_parallel_workers"`
+	SourceDbType       string      `yaml:"source_db_type"`
+	TargetDbType       string      `yaml:"target_db_type"`
+	Defaults           JobConfig   `yaml:"defaults"`
+	Jobs               []yaml.Node `yaml:"jobs"`
+}
+
+func (c *MigrationConfig) UnmarshalYAML(value *yaml.Node) error {
+	var raw rawConfig
+	if err := value.Decode(&raw); err != nil {
+		return err
+	}
+
+	c.MaxParallelWorkers = raw.MaxParallelWorkers
+	c.Defaults = raw.Defaults
+	c.SourceDbType = raw.SourceDbType
+	c.TargetDbType = raw.TargetDbType
+	c.Defaults.RowsPerPartition = int64(raw.Defaults.ExtractorBatchSize * raw.Defaults.BatchesPerPartition)
+
+	for _, node := range raw.Jobs {
+		job := Job{
+			JobConfig: raw.Defaults,
+		}
+
+		if err := node.Decode(&job); err != nil {
+			return err
+		}
+
+		job.RowsPerPartition = int64(job.ExtractorBatchSize * job.BatchesPerPartition)
+
+		c.Jobs = append(c.Jobs, job)
+	}
+
+	return nil
+}
+
+const defaultConfigFileName string = "config.yaml"
+
+func filenamesOrDefault(filenames []string) []string {
+	if len(filenames) == 0 {
+		return []string{defaultConfigFileName}
+	}
+	return filenames
+}
+
+func ReadMigrationConfig(filenames ...string) (MigrationConfig, error) {
+	filenames = filenamesOrDefault(filenames)
+	var data []byte
+	var err error
+
+	for _, filename := range filenames {
+		data, err = os.ReadFile(filename)
+		if err != nil {
+			continue
+		}
+		break
+	}
+
+	if err != nil {
+		return MigrationConfig{}, fmt.Errorf("Error reading config file: %v", err)
+	}
+
+	var config MigrationConfig
+	if err := yaml.Unmarshal(data, &config); err != nil {
+		return MigrationConfig{}, fmt.Errorf("Error parsing config file: %v", err)
+	}
+
+	return config, nil
+}

internal/app/convert/main.go

@@ -0,0 +1,18 @@
+package convert
+
+func ToInt64(v any) (int64, bool) {
+	switch t := v.(type) {
+	case int:
+		return int64(t), true
+	case int8:
+		return int64(t), true
+	case int16:
+		return int64(t), true
+	case int32:
+		return int64(t), true
+	case int64:
+		return int64(t), true
+	default:
+		return 0, false
+	}
+}

internal/app/custom_errors/backoff.go

@@ -0,0 +1,41 @@
+package custom_errors
+
+import (
+	"math/rand"
+	"time"
+)
+
+func ComputeBackoffDelay(retryCounter int, baseDelayMs int, maxDelayMs int, maxJitterMs int) time.Duration {
+	if retryCounter < 0 {
+		retryCounter = 0
+	}
+
+	delay := max(time.Duration(baseDelayMs)*time.Millisecond, 0)
+
+	maxDelay := time.Duration(maxDelayMs) * time.Millisecond
+	for i := 0; i < retryCounter; i++ {
+		if maxDelayMs > 0 && delay >= maxDelay {
+			delay = maxDelay
+			break
+		}
+		if delay == 0 {
+			break
+		}
+		delay *= 2
+	}
+
+	if maxDelayMs > 0 && delay > maxDelay {
+		delay = maxDelay
+	}
+
+	if maxJitterMs > 0 {
+		jitter := time.Duration(rand.Intn(maxJitterMs+1)) * time.Millisecond
+		delay += jitter
+	}
+
+	if delay < 0 {
+		delay = 0
+	}
+
+	return delay
+}

internal/app/custom_errors/job.error.go

@@ -0,0 +1,47 @@
+package custom_errors
+
+import (
+	"context"
+	"fmt"
+
+	log "github.com/sirupsen/logrus"
+)
+
+type JobError struct {
+	ShouldCancelJob bool
+	Msg             string
+	Prev            error
+}
+
+func (e *JobError) Error() string {
+	if e.Prev != nil {
+		return fmt.Sprintf("%s: %v", e.Msg, e.Prev)
+	}
+
+	return e.Msg
+}
+
+func JobErrorHandler(ctx context.Context, chErrorsIn <-chan JobError) error {
+	for {
+		if ctx.Err() != nil {
+			return nil
+		}
+
+		select {
+		case <-ctx.Done():
+			return nil
+
+		case err, ok := <-chErrorsIn:
+			if !ok {
+				return nil
+			}
+
+			if err.ShouldCancelJob {
+				log.Errorf("(Fatal job error) - %v - %v", err.Msg, err.Prev)
+				return &err
+			}
+
+			log.Errorf("%v - %v", err.Msg, err.Prev)
+		}
+	}
+}

internal/app/custom_errors/types.go

@@ -0,0 +1,25 @@
+package custom_errors
+
+import (
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/models"
+)
+
+type ExtractorError struct {
+	Partition models.Partition
+	LastId    int64
+	HasLastId bool
+	Msg       string
+}
+
+func (e *ExtractorError) Error() string {
+	return e.Msg
+}
+
+type LoaderError struct {
+	Batch models.Batch
+	Msg   string
+}
+
+func (e *LoaderError) Error() string {
+	return e.Msg
+}

internal/app/db-wrapper/db_dialects/main.go

@@ -0,0 +1,7 @@
+package db_dialects
+
+const (
+	SqlServer string = "sqlserver"
+	Postgres  string = "postgres"
+	Null      string = "null"
+)

internal/app/db-wrapper/main.go

@@ -0,0 +1,19 @@
+package dbwrapper
+
+import "fmt"
+
+type Factory func() DbWrapper
+
+var drivers = make(map[string]Factory)
+
+func Register(name string, factory Factory) {
+	drivers[name] = factory
+}
+
+func New(driverType string) (DbWrapper, error) {
+	factory, ok := drivers[driverType]
+	if !ok {
+		return nil, fmt.Errorf("driver not yet supported: %s", driverType)
+	}
+	return factory(), nil
+}

internal/app/db-wrapper/mssql.go

@@ -0,0 +1,317 @@
+package dbwrapper
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+	"strings"
+
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
+	dbdialects "git.ksdemosapps.com/kylesoda/go-migrate/internal/app/db-wrapper/db_dialects"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/models"
+	mssql "github.com/microsoft/go-mssqldb"
+)
+
+func init() {
+	Register(dbdialects.SqlServer, func() DbWrapper {
+		return &mssqlDbWrapper{dialect: dbdialects.SqlServer}
+	})
+}
+
+type mssqlRowResult struct {
+	row *sql.Row
+}
+
+func (mr *mssqlRowResult) Scan(dest ...any) error {
+	return mr.row.Scan(dest...)
+}
+
+type mssqlRowsResult struct {
+	columns []string
+	rows    *sql.Rows
+}
+
+func (mr *mssqlRowsResult) Close() error {
+	return mr.rows.Close()
+}
+
+func (mr *mssqlRowsResult) Columns() ([]string, error) {
+	if mr.columns != nil {
+		return mr.columns, nil
+	}
+
+	return mr.rows.Columns()
+}
+
+func (mr *mssqlRowsResult) Err() error {
+	return mr.rows.Err()
+}
+
+func (mr *mssqlRowsResult) Next() bool {
+	return mr.rows.Next()
+}
+
+func (mr *mssqlRowsResult) Scan(dest ...any) error {
+	return mr.rows.Scan(dest...)
+}
+
+func (mr *mssqlRowsResult) Values() ([]any, error) {
+	columns, err := mr.Columns()
+	if err != nil {
+		return nil, err
+	}
+
+	rowValues := make([]any, len(columns))
+	scanArgs := make([]any, len(columns))
+	for i := range rowValues {
+		scanArgs[i] = &rowValues[i]
+	}
+
+	if err := mr.rows.Scan(scanArgs...); err != nil {
+		return nil, err
+	}
+
+	return rowValues, nil
+}
+
+type mssqlDbWrapper struct {
+	db      *sql.DB
+	dialect string
+}
+
+func (mw *mssqlDbWrapper) Connect(ctx context.Context, dbUrl string) error {
+	db, err := sql.Open("sqlserver", dbUrl)
+	if err != nil {
+		return err
+	}
+
+	if err := db.PingContext(ctx); err != nil {
+		if err := db.Close(); err != nil {
+			return err
+		}
+		return err
+	}
+
+	mw.db = db
+	return nil
+}
+
+func (mw *mssqlDbWrapper) Close() error {
+	return mw.db.Close()
+}
+
+func (mw *mssqlDbWrapper) Exec(ctx context.Context, query string, args ...any) (ExecResult, error) {
+	result, execErr := mw.db.ExecContext(ctx, query, args...)
+	if execErr != nil {
+		return ExecResult{}, execErr
+	}
+
+	affectedRows, err := result.RowsAffected()
+	if err != nil {
+		return ExecResult{}, err
+	}
+
+	return ExecResult{AffectedRows: affectedRows}, nil
+}
+
+func (mw *mssqlDbWrapper) GetDialect() string {
+	return mw.dialect
+}
+
+func (mw *mssqlDbWrapper) Query(ctx context.Context, query string, args ...any) (RowsResult, error) {
+	rows, err := mw.db.QueryContext(ctx, query, args...)
+	if err != nil {
+		return nil, err
+	}
+
+	return &mssqlRowsResult{columns: nil, rows: rows}, nil
+}
+
+func (mw *mssqlDbWrapper) QueryRow(ctx context.Context, query string, args ...any) RowResult {
+	row := mw.db.QueryRowContext(ctx, query, args...)
+	return &mssqlRowResult{row: row}
+}
+
+func (mw *mssqlDbWrapper) SaveMassive(ctx context.Context, schema string, table string, columnNames []string, rows [][]any) (int64, error) {
+	tx, err := mw.db.BeginTx(ctx, nil)
+	if err != nil {
+		return 0, err
+	}
+
+	fullTableName := fmt.Sprintf("[%s].[%s]", schema, table)
+
+	stmt, err := tx.PrepareContext(ctx, mssql.CopyIn(fullTableName, mssql.BulkOptions{}, columnNames...))
+	if err != nil {
+		tx.Rollback()
+		return 0, err
+	}
+
+	for _, row := range rows {
+		_, err = stmt.ExecContext(ctx, row...)
+		if err != nil {
+			stmt.Close()
+			tx.Rollback()
+			return 0, err
+		}
+	}
+
+	result, err := stmt.ExecContext(ctx)
+	if err != nil {
+		stmt.Close()
+		tx.Rollback()
+		return 0, err
+	}
+
+	if err := stmt.Close(); err != nil {
+		tx.Rollback()
+		return 0, err
+	}
+
+	if err := tx.Commit(); err != nil {
+		return 0, err
+	}
+
+	rowsAffected, raErr := result.RowsAffected()
+	if raErr != nil {
+		return 0, nil
+	}
+
+	return rowsAffected, nil
+}
+
+func buildExtractQueryMssql(q ExtractionQuery) (string, error) {
+	var sbQuery strings.Builder
+
+	sbQuery.WriteString("SELECT ")
+
+	hasRegularColumns := len(q.Columns) > 0
+	hasJsonColumns := len(q.FromJsonColumns) > 0
+
+	resolvedJson := make(map[string][]config.FromJsonItem, len(q.FromJsonColumns))
+	if hasJsonColumns {
+		for _, jsonConfig := range q.FromJsonColumns {
+			actualColumnName, err := findColumnByPattern(q.Columns, jsonConfig.Column)
+			if err != nil {
+				return "", err
+			}
+			resolvedJson[actualColumnName] = append(resolvedJson[actualColumnName], jsonConfig)
+		}
+	}
+
+	selectParts := make([]string, 0, len(q.Columns)+len(q.FromJsonColumns))
+	if hasRegularColumns {
+		for _, col := range q.Columns {
+			jsonConfigs, isJsonColumn := resolvedJson[col.Name()]
+			if isJsonColumn {
+				for _, jsonConfig := range jsonConfigs {
+					jsonPath := buildJsonPathMssql(jsonConfig.Field)
+					jsonExpr := fmt.Sprintf("JSON_VALUE([%s], '%s') AS [%s]", col.Name(), jsonPath, col.Name())
+					selectParts = append(selectParts, jsonExpr)
+				}
+				continue
+			}
+
+			colExpr := fmt.Sprintf("[%s]", col.Name())
+			switch col.Type() {
+			case "GEOMETRY":
+				colExpr = fmt.Sprintf("[%s].STAsBinary() AS [%s]", col.Name(), col.Name())
+			}
+			selectParts = append(selectParts, colExpr)
+		}
+	} else if !hasJsonColumns {
+		selectParts = append(selectParts, "*")
+	}
+
+	for i, part := range selectParts {
+		sbQuery.WriteString(part)
+		if i < len(selectParts)-1 {
+			sbQuery.WriteString(", ")
+		}
+	}
+
+	fmt.Fprintf(&sbQuery, " FROM [%s].[%s]", q.Schema, q.Table)
+
+	if q.LowerLimit.IsValid || q.UpperLimit.IsValid {
+		sbQuery.WriteString(" WHERE ")
+
+		if q.LowerLimit.IsValid {
+			fmt.Fprintf(&sbQuery, "[%s]", q.PrimaryKey)
+			if q.LowerLimit.IsInclusive {
+				sbQuery.WriteString(" >=")
+			} else {
+				sbQuery.WriteString(" >")
+			}
+			sbQuery.WriteString(" @min")
+		}
+
+		if q.LowerLimit.IsValid && q.UpperLimit.IsValid {
+			sbQuery.WriteString(" AND ")
+		}
+
+		if q.UpperLimit.IsValid {
+			fmt.Fprintf(&sbQuery, "[%s]", q.PrimaryKey)
+			if q.UpperLimit.IsInclusive {
+				sbQuery.WriteString(" <=")
+			} else {
+				sbQuery.WriteString(" <")
+			}
+			sbQuery.WriteString(" @max")
+		}
+	}
+
+	fmt.Fprintf(&sbQuery, " ORDER BY [%s] ASC", q.PrimaryKey)
+
+	return sbQuery.String(), nil
+}
+
+func findColumnByPattern(columns []models.ColumnType, pattern string) (string, error) {
+	if pattern == "" {
+		return "", fmt.Errorf("column pattern cannot be empty")
+	}
+
+	if before, ok := strings.CutSuffix(pattern, "*"); ok {
+		prefix := before
+		for _, col := range columns {
+			if strings.HasPrefix(col.Name(), prefix) {
+				return col.Name(), nil
+			}
+		}
+		return "", fmt.Errorf("no column found matching pattern '%s'", pattern)
+	}
+
+	for _, col := range columns {
+		if col.Name() == pattern {
+			return col.Name(), nil
+		}
+	}
+	return "", fmt.Errorf("column '%s' not found in table columns", pattern)
+}
+
+func (mw *mssqlDbWrapper) QueryFromObject(ctx context.Context, q ExtractionQuery) (RowsResult, error) {
+	queryString, err := buildExtractQueryMssql(q)
+	if err != nil {
+		return nil, err
+	}
+
+	// logrus.Debugf("Query: %s", queryString)
+
+	var queryArgs []any
+
+	if q.LowerLimit.IsValid {
+		queryArgs = append(queryArgs, sql.Named("min", q.LowerLimit.Value))
+	}
+
+	if q.UpperLimit.IsValid {
+		queryArgs = append(queryArgs, sql.Named("max", q.UpperLimit.Value))
+	}
+
+	return mw.Query(ctx, queryString, queryArgs...)
+}
+
+func buildJsonPathMssql(field string) string {
+	if len(field) > 0 && field[0] == '.' {
+		field = field[1:]
+	}
+
+	return "$." + field
+}

internal/app/db-wrapper/mssql_test.go

@@ -0,0 +1,396 @@
+package dbwrapper
+
+import (
+	"strings"
+	"testing"
+
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/models"
+)
+
+func TestBuildExtractQueryMssql_NoJsonColumns(t *testing.T) {
+	q := ExtractionQuery{
+		Schema:     "dbo",
+		Table:      "Users",
+		PrimaryKey: "ID",
+		Columns: []models.ColumnType{
+			models.NewColumnType("ID", false, false, "INT", "int", "INT", false, 0, 0, 0),
+			models.NewColumnType("Name", true, false, "VARCHAR", "varchar", "VARCHAR", true, 255, 0, 0),
+		},
+		FromJsonColumns: []config.FromJsonItem{},
+		LowerLimit:      ExtractorQueryLimit{IsValid: false},
+		UpperLimit:      ExtractorQueryLimit{IsValid: false},
+	}
+
+	query, err := buildExtractQueryMssql(q)
+	if err != nil {
+		t.Fatalf("Expected no error, got: %v", err)
+	}
+
+	if !strings.Contains(query, "SELECT [ID], [Name]") {
+		t.Errorf("Expected columns in query, got: %s", query)
+	}
+
+	if !strings.Contains(query, "FROM [dbo].[Users]") {
+		t.Errorf("Expected FROM clause, got: %s", query)
+	}
+
+	if !strings.Contains(query, "ORDER BY [ID] ASC") {
+		t.Errorf("Expected ORDER BY clause, got: %s", query)
+	}
+}
+
+func TestBuildExtractQueryMssql_WithJsonColumns_ExactColumnMatch(t *testing.T) {
+	// Test that the actual column name is used as alias, not a generated one
+	q := ExtractionQuery{
+		Schema:     "dbo",
+		Table:      "Events",
+		PrimaryKey: "EventID",
+		Columns: []models.ColumnType{
+			models.NewColumnType("EventID", false, false, "INT", "int", "INT", false, 0, 0, 0),
+			models.NewColumnType("EventData", true, false, "VARCHAR", "varchar", "VARCHAR", true, 500, 0, 0),
+		},
+		FromJsonColumns: []config.FromJsonItem{
+			{Column: "EventData", Field: ".userId"},
+			{Column: "EventData", Field: ".timestamp"},
+		},
+		LowerLimit: ExtractorQueryLimit{IsValid: false},
+		UpperLimit: ExtractorQueryLimit{IsValid: false},
+	}
+
+	query, err := buildExtractQueryMssql(q)
+	if err != nil {
+		t.Fatalf("Expected no error, got: %v", err)
+	}
+
+	if !strings.HasPrefix(query, "SELECT [EventID], JSON_VALUE([EventData], '$.userId') AS [EventData], JSON_VALUE([EventData], '$.timestamp') AS [EventData]") {
+		t.Errorf("Expected JSON columns to replace EventData in-order, got: %s", query)
+	}
+
+	if strings.Contains(query, "SELECT [EventID], [EventData]") {
+		t.Errorf("Expected EventData to be replaced by JSON extraction, got: %s", query)
+	}
+
+	// Alias should be exactly "EventData", not "EventData_userId"
+	if !strings.Contains(query, "JSON_VALUE([EventData], '$.userId') AS [EventData]") {
+		t.Errorf("Expected JSON alias to be [EventData], got: %s", query)
+	}
+
+	if !strings.Contains(query, "JSON_VALUE([EventData], '$.timestamp') AS [EventData]") {
+		t.Errorf("Expected JSON alias to be [EventData], got: %s", query)
+	}
+
+	// Should have comma separating them
+	if !strings.Contains(query, "JSON_VALUE([EventData], '$.userId') AS [EventData], JSON_VALUE([EventData], '$.timestamp') AS [EventData]") {
+		t.Errorf("Expected comma-separated JSON values, got: %s", query)
+	}
+}
+
+func TestBuildExtractQueryMssql_WithWildcardPattern(t *testing.T) {
+	// Test that wildcard pattern matching finds the correct column
+	q := ExtractionQuery{
+		Schema:     "dbo",
+		Table:      "Events",
+		PrimaryKey: "ID",
+		Columns: []models.ColumnType{
+			models.NewColumnType("ID", false, false, "INT", "int", "INT", false, 0, 0, 0),
+			models.NewColumnType("NodeMetadata", true, false, "VARCHAR", "varchar", "VARCHAR", true, 500, 0, 0),
+		},
+		FromJsonColumns: []config.FromJsonItem{
+			{Column: "NodeMeta*", Field: ".id"},
+		},
+		LowerLimit: ExtractorQueryLimit{IsValid: false},
+		UpperLimit: ExtractorQueryLimit{IsValid: false},
+	}
+
+	query, err := buildExtractQueryMssql(q)
+	if err != nil {
+		t.Fatalf("Expected no error, got: %v", err)
+	}
+
+	// Should find "NodeMetadata" from pattern "NodeMeta*" and use it as alias
+	if !strings.Contains(query, "JSON_VALUE([NodeMetadata], '$.id') AS [NodeMetadata]") {
+		t.Errorf("Expected to find and use NodeMetadata column by pattern, got: %s", query)
+	}
+
+	if strings.Contains(query, "SELECT [ID], [NodeMetadata]") {
+		t.Errorf("Expected NodeMetadata to be replaced by JSON extraction, got: %s", query)
+	}
+}
+
+func TestBuildExtractQueryMssql_ColumnNotFound_Error(t *testing.T) {
+	// Test that an error is returned when column is not found
+	q := ExtractionQuery{
+		Schema:     "dbo",
+		Table:      "Events",
+		PrimaryKey: "ID",
+		Columns: []models.ColumnType{
+			models.NewColumnType("ID", false, false, "INT", "int", "INT", false, 0, 0, 0),
+		},
+		FromJsonColumns: []config.FromJsonItem{
+			{Column: "NonExistentColumn", Field: ".id"},
+		},
+		LowerLimit: ExtractorQueryLimit{IsValid: false},
+		UpperLimit: ExtractorQueryLimit{IsValid: false},
+	}
+
+	query, err := buildExtractQueryMssql(q)
+	if err == nil {
+		t.Fatalf("Expected error for missing column, got no error. Query: %s", query)
+	}
+
+	if !strings.Contains(err.Error(), "NonExistentColumn") {
+		t.Errorf("Expected error message to contain column name, got: %v", err)
+	}
+}
+
+func TestBuildExtractQueryMssql_WildcardPatternNotMatched_Error(t *testing.T) {
+	// Test that an error is returned when wildcard pattern doesn't match any column
+	q := ExtractionQuery{
+		Schema:     "dbo",
+		Table:      "Events",
+		PrimaryKey: "ID",
+		Columns: []models.ColumnType{
+			models.NewColumnType("ID", false, false, "INT", "int", "INT", false, 0, 0, 0),
+			models.NewColumnType("EventData", true, false, "VARCHAR", "varchar", "VARCHAR", true, 500, 0, 0),
+		},
+		FromJsonColumns: []config.FromJsonItem{
+			{Column: "NonMatching*", Field: ".id"},
+		},
+		LowerLimit: ExtractorQueryLimit{IsValid: false},
+		UpperLimit: ExtractorQueryLimit{IsValid: false},
+	}
+
+	query, err := buildExtractQueryMssql(q)
+	if err == nil {
+		t.Fatalf("Expected error for non-matching wildcard pattern, got no error. Query: %s", query)
+	}
+
+	if !strings.Contains(err.Error(), "NonMatching*") {
+		t.Errorf("Expected error message to contain pattern, got: %v", err)
+	}
+}
+
+func TestBuildExtractQueryMssql_NestedJsonFields(t *testing.T) {
+	q := ExtractionQuery{
+		Schema:     "dbo",
+		Table:      "Data",
+		PrimaryKey: "ID",
+		Columns: []models.ColumnType{
+			models.NewColumnType("ID", false, false, "INT", "int", "INT", false, 0, 0, 0),
+			models.NewColumnType("NodeData", true, false, "VARCHAR", "varchar", "VARCHAR", true, 500, 0, 0),
+		},
+		FromJsonColumns: []config.FromJsonItem{
+			{Column: "NodeData", Field: ".user.name"},
+			{Column: "NodeData", Field: ".user.email"},
+		},
+		LowerLimit: ExtractorQueryLimit{IsValid: false},
+		UpperLimit: ExtractorQueryLimit{IsValid: false},
+	}
+
+	query, err := buildExtractQueryMssql(q)
+	if err != nil {
+		t.Fatalf("Expected no error, got: %v", err)
+	}
+
+	if !strings.Contains(query, "JSON_VALUE([NodeData], '$.user.name') AS [NodeData]") {
+		t.Errorf("Expected nested JSON path for user.name, got: %s", query)
+	}
+
+	if !strings.Contains(query, "JSON_VALUE([NodeData], '$.user.email') AS [NodeData]") {
+		t.Errorf("Expected nested JSON path for user.email, got: %s", query)
+	}
+
+	if strings.Contains(query, "SELECT [ID], [NodeData]") {
+		t.Errorf("Expected NodeData to be replaced by JSON extraction, got: %s", query)
+	}
+}
+
+func TestBuildExtractQueryMssql_WithRangeLimits(t *testing.T) {
+	q := ExtractionQuery{
+		Schema:     "dbo",
+		Table:      "Products",
+		PrimaryKey: "ProductID",
+		Columns: []models.ColumnType{
+			models.NewColumnType("ProductID", false, false, "INT", "int", "INT", false, 0, 0, 0),
+			models.NewColumnType("Details", true, false, "VARCHAR", "varchar", "VARCHAR", true, 500, 0, 0),
+		},
+		FromJsonColumns: []config.FromJsonItem{
+			{Column: "Details", Field: ".price"},
+		},
+		LowerLimit: ExtractorQueryLimit{IsValid: true, IsInclusive: true, Value: 100},
+		UpperLimit: ExtractorQueryLimit{IsValid: true, IsInclusive: false, Value: 500},
+	}
+
+	query, err := buildExtractQueryMssql(q)
+	if err != nil {
+		t.Fatalf("Expected no error, got: %v", err)
+	}
+
+	if !strings.Contains(query, "WHERE [ProductID] >= @min") {
+		t.Errorf("Expected WHERE clause with >=, got: %s", query)
+	}
+
+	if !strings.Contains(query, "[ProductID] < @max") {
+		t.Errorf("Expected upper limit with <, got: %s", query)
+	}
+
+	if !strings.Contains(query, "JSON_VALUE([Details], '$.price') AS [Details]") {
+		t.Errorf("Expected JSON_VALUE for Details, got: %s", query)
+	}
+
+	if strings.Contains(query, "SELECT [ProductID], [Details]") {
+		t.Errorf("Expected Details to be replaced by JSON extraction, got: %s", query)
+	}
+}
+
+func TestBuildJsonPathMssql(t *testing.T) {
+	tests := []struct {
+		input    string
+		expected string
+	}{
+		{".id", "$.id"},
+		{"id", "$.id"},
+		{".user.name", "$.user.name"},
+		{"user.name", "$.user.name"},
+		{".location.coordinates.lat", "$.location.coordinates.lat"},
+		{"", "$."},
+	}
+
+	for _, tt := range tests {
+		result := buildJsonPathMssql(tt.input)
+		if result != tt.expected {
+			t.Errorf("buildJsonPathMssql(%q) = %q, want %q", tt.input, result, tt.expected)
+		}
+	}
+}
+
+func TestFindColumnByPattern_ExactMatch(t *testing.T) {
+	columns := []models.ColumnType{
+		models.NewColumnType("ID", false, false, "INT", "int", "INT", false, 0, 0, 0),
+		models.NewColumnType("Metadata", true, false, "VARCHAR", "varchar", "VARCHAR", true, 500, 0, 0),
+		models.NewColumnType("EventData", true, false, "VARCHAR", "varchar", "VARCHAR", true, 500, 0, 0),
+	}
+
+	result, err := findColumnByPattern(columns, "Metadata")
+	if err != nil {
+		t.Fatalf("Expected no error, got: %v", err)
+	}
+
+	if result != "Metadata" {
+		t.Errorf("Expected 'Metadata', got '%s'", result)
+	}
+}
+
+func TestFindColumnByPattern_WildcardMatch(t *testing.T) {
+	columns := []models.ColumnType{
+		models.NewColumnType("ID", false, false, "INT", "int", "INT", false, 0, 0, 0),
+		models.NewColumnType("NodeMetadata", true, false, "VARCHAR", "varchar", "VARCHAR", true, 500, 0, 0),
+		models.NewColumnType("EventData", true, false, "VARCHAR", "varchar", "VARCHAR", true, 500, 0, 0),
+	}
+
+	result, err := findColumnByPattern(columns, "NodeMeta*")
+	if err != nil {
+		t.Fatalf("Expected no error, got: %v", err)
+	}
+
+	if result != "NodeMetadata" {
+		t.Errorf("Expected 'NodeMetadata', got '%s'", result)
+	}
+}
+
+func TestFindColumnByPattern_NotFound(t *testing.T) {
+	columns := []models.ColumnType{
+		models.NewColumnType("ID", false, false, "INT", "int", "INT", false, 0, 0, 0),
+		models.NewColumnType("Metadata", true, false, "VARCHAR", "varchar", "VARCHAR", true, 500, 0, 0),
+	}
+
+	result, err := findColumnByPattern(columns, "NonExistent")
+	if err == nil {
+		t.Fatalf("Expected error, got no error. Result: %s", result)
+	}
+
+	if !strings.Contains(err.Error(), "NonExistent") {
+		t.Errorf("Expected error to contain column name, got: %v", err)
+	}
+}
+
+func TestFindColumnByPattern_WildcardNotFound(t *testing.T) {
+	columns := []models.ColumnType{
+		models.NewColumnType("ID", false, false, "INT", "int", "INT", false, 0, 0, 0),
+		models.NewColumnType("Metadata", true, false, "VARCHAR", "varchar", "VARCHAR", true, 500, 0, 0),
+	}
+
+	result, err := findColumnByPattern(columns, "Event*")
+	if err == nil {
+		t.Fatalf("Expected error, got no error. Result: %s", result)
+	}
+
+	if !strings.Contains(err.Error(), "Event*") {
+		t.Errorf("Expected error to contain pattern, got: %v", err)
+	}
+}
+
+func TestBuildExtractQueryMssql_OnlyJsonColumns(t *testing.T) {
+	// Test when all columns are used via JSON extraction
+	q := ExtractionQuery{
+		Schema:     "dbo",
+		Table:      "Data",
+		PrimaryKey: "ID",
+		Columns: []models.ColumnType{
+			models.NewColumnType("ID", false, false, "INT", "int", "INT", false, 0, 0, 0),
+			models.NewColumnType("JsonData", true, false, "VARCHAR", "varchar", "VARCHAR", true, 500, 0, 0),
+		},
+		FromJsonColumns: []config.FromJsonItem{
+			{Column: "JsonData", Field: ".field1"},
+		},
+		LowerLimit: ExtractorQueryLimit{IsValid: false},
+		UpperLimit: ExtractorQueryLimit{IsValid: false},
+	}
+
+	query, err := buildExtractQueryMssql(q)
+	if err != nil {
+		t.Fatalf("Expected no error, got: %v", err)
+	}
+
+	if !strings.HasPrefix(query, "SELECT [ID], JSON_VALUE([JsonData], '$.field1') AS [JsonData]") {
+		t.Errorf("Expected JsonData to be replaced by JSON extraction, got: %s", query)
+	}
+
+	if strings.Contains(query, "SELECT [ID], [JsonData]") {
+		t.Errorf("Expected JsonData to be excluded from raw selection, got: %s", query)
+	}
+}
+
+func TestBuildExtractQueryMssql_JsonColumnsReplaceInOrder(t *testing.T) {
+	q := ExtractionQuery{
+		Schema:     "dbo",
+		Table:      "Users",
+		PrimaryKey: "UserID",
+		Columns: []models.ColumnType{
+			models.NewColumnType("UserID", false, false, "INT", "int", "INT", false, 0, 0, 0),
+			models.NewColumnType("Name", true, false, "VARCHAR", "varchar", "VARCHAR", false, 255, 0, 0),
+			models.NewColumnType("Email", true, false, "VARCHAR", "varchar", "VARCHAR", false, 255, 0, 0),
+			models.NewColumnType("Metadata", true, false, "NVARCHAR", "nvarchar", "NVARCHAR", true, 4000, 0, 0),
+			models.NewColumnType("Profile", true, false, "NVARCHAR", "nvarchar", "NVARCHAR", true, 4000, 0, 0),
+			models.NewColumnType("Settings", true, false, "NVARCHAR", "nvarchar", "NVARCHAR", true, 4000, 0, 0),
+		},
+		FromJsonColumns: []config.FromJsonItem{
+			{Column: "Metadata", Field: ".id"},
+			{Column: "Profile", Field: ".id"},
+			{Column: "Settings", Field: ".id"},
+		},
+		LowerLimit: ExtractorQueryLimit{IsValid: false},
+		UpperLimit: ExtractorQueryLimit{IsValid: false},
+	}
+
+	query, err := buildExtractQueryMssql(q)
+	if err != nil {
+		t.Fatalf("Expected no error, got: %v", err)
+	}
+
+	expected := "SELECT [UserID], [Name], [Email], JSON_VALUE([Metadata], '$.id') AS [Metadata], JSON_VALUE([Profile], '$.id') AS [Profile], JSON_VALUE([Settings], '$.id') AS [Settings] FROM [dbo].[Users] ORDER BY [UserID] ASC"
+	if query != expected {
+		t.Errorf("Unexpected query.\nExpected: %s\nGot: %s", expected, query)
+	}
+}

internal/app/db-wrapper/postgres.go

@@ -0,0 +1,203 @@
+package dbwrapper
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"strings"
+
+	dbdialects "git.ksdemosapps.com/kylesoda/go-migrate/internal/app/db-wrapper/db_dialects"
+	"github.com/jackc/pgx/v5"
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+func init() {
+	Register(dbdialects.Postgres, func() DbWrapper {
+		return &postgresDbWrapper{dialect: dbdialects.Postgres}
+	})
+}
+
+type postgresRowResult struct {
+	row pgx.Row
+}
+
+func (pr *postgresRowResult) Scan(dest ...any) error {
+	return pr.row.Scan(dest...)
+}
+
+type postgresRowsResult struct {
+	columns []string
+	rows    pgx.Rows
+}
+
+func (pr *postgresRowsResult) Close() error {
+	pr.rows.Close()
+	return nil
+}
+
+func (pr *postgresRowsResult) Columns() ([]string, error) {
+	if pr.columns != nil {
+		return pr.columns, nil
+	}
+
+	rawColumns := pr.rows.FieldDescriptions()
+	if rawColumns == nil {
+		return nil, errors.New("error retrieving columns")
+	}
+
+	columns := make([]string, 0, len(rawColumns))
+	for _, rc := range rawColumns {
+		columns = append(columns, rc.Name)
+	}
+
+	return columns, nil
+}
+
+func (pr *postgresRowsResult) Err() error {
+	return pr.rows.Err()
+}
+
+func (pr *postgresRowsResult) Next() bool {
+	return pr.rows.Next()
+}
+
+func (pr *postgresRowsResult) Scan(dest ...any) error {
+	return pr.rows.Scan(dest...)
+}
+
+func (pr *postgresRowsResult) Values() ([]any, error) {
+	return pr.rows.Values()
+}
+
+type postgresDbWrapper struct {
+	db      *pgxpool.Pool
+	dialect string
+}
+
+func (pw *postgresDbWrapper) Connect(ctx context.Context, dbUrl string) error {
+	pool, err := pgxpool.New(ctx, dbUrl)
+	if err != nil {
+		return err
+	}
+
+	if err := pool.Ping(ctx); err != nil {
+		pool.Close()
+		return err
+	}
+
+	pw.db = pool
+	return nil
+}
+
+func (pw *postgresDbWrapper) Close() error {
+	pw.db.Close()
+	return nil
+}
+
+func (pw *postgresDbWrapper) Exec(ctx context.Context, query string, args ...any) (ExecResult, error) {
+	result, err := pw.db.Exec(ctx, query, args...)
+	if err != nil {
+		return ExecResult{}, err
+	}
+
+	return ExecResult{AffectedRows: result.RowsAffected()}, nil
+}
+
+func (pw *postgresDbWrapper) GetDialect() string {
+	return pw.dialect
+}
+
+func (pw *postgresDbWrapper) Query(ctx context.Context, query string, args ...any) (RowsResult, error) {
+	rows, err := pw.db.Query(ctx, query, args...)
+	if err != nil {
+		return nil, err
+	}
+
+	return &postgresRowsResult{columns: nil, rows: rows}, nil
+}
+
+func (pw *postgresDbWrapper) QueryRow(ctx context.Context, query string, args ...any) RowResult {
+	row := pw.db.QueryRow(ctx, query, args...)
+	return &postgresRowResult{row: row}
+}
+
+func (pw *postgresDbWrapper) SaveMassive(ctx context.Context, schema string, table string, columnNames []string, rows [][]any) (int64, error) {
+	affectedRows, err := pw.db.CopyFrom(ctx, pgx.Identifier{schema, table}, columnNames, pgx.CopyFromRows(rows))
+	if err != nil {
+		return 0, err
+	}
+
+	return affectedRows, nil
+}
+
+func (pw *postgresDbWrapper) QueryFromObject(ctx context.Context, q ExtractionQuery) (RowsResult, error) {
+	var sbQuery strings.Builder
+
+	sbQuery.WriteString("SELECT ")
+
+	if len(q.Columns) == 0 {
+		sbQuery.WriteString("*")
+	} else {
+		for i, col := range q.Columns {
+			switch col.Type() {
+			case "GEOMETRY":
+				fmt.Fprintf(&sbQuery, `ST_AsEWKB("%s") AS "%s"`, col.Name(), col.Name())
+			default:
+				fmt.Fprintf(&sbQuery, `"%s"`, col.Name())
+			}
+
+			if i < len(q.Columns)-1 {
+				sbQuery.WriteString(", ")
+			}
+		}
+	}
+
+	fmt.Fprintf(&sbQuery, ` FROM "%s"."%s"`, q.Schema, q.Table)
+
+	if q.LowerLimit.IsValid || q.UpperLimit.IsValid {
+		sbQuery.WriteString(" WHERE ")
+		paramIdx := 1
+
+		if q.LowerLimit.IsValid {
+			fmt.Fprintf(&sbQuery, `"%s"`, q.PrimaryKey)
+			if q.LowerLimit.IsInclusive {
+				sbQuery.WriteString(" >=")
+			} else {
+				sbQuery.WriteString(" >")
+			}
+			fmt.Fprintf(&sbQuery, " $%d", paramIdx)
+			paramIdx++
+		}
+
+		if q.LowerLimit.IsValid && q.UpperLimit.IsValid {
+			sbQuery.WriteString(" AND ")
+		}
+
+		if q.UpperLimit.IsValid {
+			fmt.Fprintf(&sbQuery, `"%s"`, q.PrimaryKey)
+			if q.UpperLimit.IsInclusive {
+				sbQuery.WriteString(" <=")
+			} else {
+				sbQuery.WriteString(" <")
+			}
+			fmt.Fprintf(&sbQuery, " $%d", paramIdx)
+			paramIdx++
+		}
+	}
+
+	fmt.Fprintf(&sbQuery, ` ORDER BY "%s" ASC`, q.PrimaryKey)
+
+	queryString := sbQuery.String()
+
+	var queryArgs []any
+
+	if q.LowerLimit.IsValid {
+		queryArgs = append(queryArgs, q.LowerLimit.Value)
+	}
+
+	if q.UpperLimit.IsValid {
+		queryArgs = append(queryArgs, q.UpperLimit.Value)
+	}
+
+	return pw.Query(ctx, queryString, queryArgs...)
+}

internal/app/db-wrapper/types.go

@@ -0,0 +1,55 @@
+package dbwrapper
+
+import (
+	"context"
+	"errors"
+
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/models"
+)
+
+var MethodNotSupported error = errors.New("Method not supported by driver... yet :P")
+
+type ExecResult struct {
+	AffectedRows int64
+}
+
+type RowsResult interface {
+	Close() error
+	Columns() ([]string, error)
+	Err() error
+	Next() bool
+	Scan(dest ...any) error
+	Values() ([]any, error)
+}
+
+type RowResult interface {
+	Scan(dest ...any) error
+}
+
+type ExtractorQueryLimit struct {
+	IsValid     bool
+	IsInclusive bool
+	Value       int64
+}
+
+type ExtractionQuery struct {
+	Schema          string
+	Table           string
+	PrimaryKey      string
+	Columns         []models.ColumnType
+	LowerLimit      ExtractorQueryLimit
+	UpperLimit      ExtractorQueryLimit
+	FromJsonColumns []config.FromJsonItem
+}
+
+type DbWrapper interface {
+	Close() error
+	Connect(ctx context.Context, dbUrl string) error
+	Exec(ctx context.Context, query string, args ...any) (ExecResult, error)
+	GetDialect() string
+	Query(ctx context.Context, query string, args ...any) (RowsResult, error)
+	QueryRow(ctx context.Context, query string, args ...any) RowResult
+	SaveMassive(ctx context.Context, schema string, table string, columnNames []string, rows [][]any) (int64, error)
+	QueryFromObject(ctx context.Context, query ExtractionQuery) (RowsResult, error)
+}

internal/app/db/postgres.go

@@ -1,28 +0,0 @@
-package db
-
-import (
-	"context"
-	"fmt"
-
-	"github.com/jackc/pgx/v5/pgxpool"
-)
-
-func Connect(ctx context.Context, dbURL string) (*pgxpool.Pool, error) {
-	pool, err := pgxpool.New(ctx, dbURL)
-	if err != nil {
-		return nil, fmt.Errorf("unable to connect to database: %w", err)
-	}
-
-	if err := pool.Ping(ctx); err != nil {
-		pool.Close()
-		return nil, fmt.Errorf("unable to ping database: %w", err)
-	}
-
-	return pool, nil
-}
-
-func Close(pool *pgxpool.Pool) {
-	if pool != nil {
-		pool.Close()
-	}
-}

internal/app/etl/extractors/consume.go

@@ -0,0 +1,108 @@
+package extractors
+
+import (
+	"context"
+	"errors"
+	"slices"
+	"strings"
+	"sync"
+	"sync/atomic"
+
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/custom_errors"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/models"
+	"github.com/sirupsen/logrus"
+)
+
+func (ex *GenericExtractor) Consume(
+	ctx context.Context,
+	tableInfo config.SourceTableInfo,
+	columns []models.ColumnType,
+	batchSize int,
+	retryConfig config.RetryConfig,
+	chPartitionsIn <-chan models.Partition,
+	chBatchesOut chan<- models.Batch,
+	chErrorsOut chan<- custom_errors.JobError,
+	wgActivePartitions *sync.WaitGroup,
+	rowsRead *int64,
+	failedPartitionsCount *int32,
+	fromJsonColumns []config.FromJsonItem,
+) {
+	indexPrimaryKey := slices.IndexFunc(columns, func(col models.ColumnType) bool {
+		return strings.EqualFold(col.Name(), tableInfo.PrimaryKey)
+	})
+
+	if indexPrimaryKey == -1 {
+		select {
+		case <-ctx.Done():
+			return
+		case chErrorsOut <- custom_errors.JobError{
+			ShouldCancelJob: true,
+			Msg:             "Primary key not found in provided columns",
+		}:
+		}
+
+		return
+	}
+
+	for {
+		if ctx.Err() != nil {
+			return
+		}
+
+		select {
+		case <-ctx.Done():
+			return
+		case partition, ok := <-chPartitionsIn:
+			if !ok {
+				return
+			}
+
+			rowsReadResult, err := ex.ProcessPartitionWithRetries(
+				ctx,
+				tableInfo,
+				columns,
+				batchSize,
+				partition,
+				indexPrimaryKey,
+				retryConfig,
+				chBatchesOut,
+				fromJsonColumns,
+			)
+			wgActivePartitions.Done()
+
+			if rowsReadResult > 0 {
+				current := atomic.LoadInt64(rowsRead)
+				logrus.Debugf("Rows read (partition extracted): +%v [current=%v] (%s.%s)", rowsReadResult, current, tableInfo.Schema, tableInfo.Table)
+				atomic.AddInt64(rowsRead, int64(rowsReadResult))
+			}
+
+			if err != nil {
+				atomic.AddInt32(failedPartitionsCount, 1)
+				if jobError, ok := errors.AsType[*custom_errors.JobError](err); ok {
+					select {
+					case <-ctx.Done():
+						return
+					case chErrorsOut <- *jobError:
+					}
+				} else {
+					select {
+					case <-ctx.Done():
+						return
+					case chErrorsOut <- custom_errors.JobError{ShouldCancelJob: false, Msg: err.Error(), Prev: err}:
+					}
+				}
+
+				currentFPCount := atomic.LoadInt32(failedPartitionsCount)
+				if currentFPCount > int32(retryConfig.MaxFailedPartitions) {
+					select {
+					case <-ctx.Done():
+						return
+					case chErrorsOut <- custom_errors.JobError{ShouldCancelJob: true, Msg: "Max failed partitions reached"}:
+						return
+					}
+				}
+			}
+		}
+	}
+}

internal/app/etl/extractors/main.go

@@ -0,0 +1,41 @@
+package extractors
+
+import (
+	"context"
+
+	dbwrapper "git.ksdemosapps.com/kylesoda/go-migrate/internal/app/db-wrapper"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/models"
+	"github.com/google/uuid"
+)
+
+type GenericExtractor struct {
+	db dbwrapper.DbWrapper
+}
+
+func NewExtractor(db dbwrapper.DbWrapper) GenericExtractor {
+	return GenericExtractor{db: db}
+}
+
+func sendBatch(ctx context.Context, chBatchesOut chan<- models.Batch, batch models.Batch) error {
+	select {
+	case chBatchesOut <- batch:
+		return nil
+	case <-ctx.Done():
+		return ctx.Err()
+	}
+}
+
+func flush(
+	ctx context.Context,
+	batchSize int,
+	batchRows []models.UnknownRowValues,
+	chBatchesOut chan<- models.Batch,
+) error {
+	if len(batchRows) == 0 {
+		return nil
+	}
+
+	batch := models.Batch{Id: uuid.New(), Rows: batchRows}
+	batchRows = make([]models.UnknownRowValues, 0, batchSize)
+	return sendBatch(ctx, chBatchesOut, batch)
+}

internal/app/etl/extractors/process-with-retries.go

@@ -0,0 +1,77 @@
+package extractors
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"time"
+
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/custom_errors"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/models"
+	"github.com/google/uuid"
+	// "github.com/sirupsen/logrus"
+)
+
+func (ex *GenericExtractor) ProcessPartitionWithRetries(
+	ctx context.Context,
+	tableInfo config.SourceTableInfo,
+	columns []models.ColumnType,
+	batchSize int,
+	partition models.Partition,
+	indexPrimaryKey int,
+	retryConfig config.RetryConfig,
+	chBatchesOut chan<- models.Batch,
+	fromJsonColumns []config.FromJsonItem,
+) (int64, error) {
+	var totalRowsRead int64
+	currentParitition := partition
+
+	for {
+		rowsRead, err := ex.ProcessPartition(
+			ctx,
+			tableInfo,
+			columns,
+			batchSize,
+			currentParitition,
+			indexPrimaryKey,
+			chBatchesOut,
+			fromJsonColumns,
+		)
+		// logrus.Debugf("Partition %v finished processing (%s.%s)", partition.Id, tableInfo.Schema, tableInfo.Table)
+		totalRowsRead += rowsRead
+
+		if err == nil {
+			return totalRowsRead, nil
+		}
+
+		if exError, ok := errors.AsType[*custom_errors.ExtractorError](err); ok {
+			currentParitition.RetryCounter++
+
+			if currentParitition.RetryCounter >= retryConfig.Attempts {
+				return totalRowsRead, &custom_errors.JobError{
+					Msg:  fmt.Sprintf("Partition %v reached max retries (%d)", currentParitition.Id, currentParitition.RetryCounter),
+					Prev: err,
+				}
+			}
+
+			if exError.HasLastId {
+				currentParitition.ParentId = exError.Partition.Id
+				currentParitition.Id = uuid.New()
+				currentParitition.Range.Min = exError.LastId
+				currentParitition.Range.IsMinInclusive = false
+			}
+
+			delay := custom_errors.ComputeBackoffDelay(
+				currentParitition.RetryCounter,
+				retryConfig.BaseDelayMs,
+				retryConfig.MaxDelayMs,
+				retryConfig.MaxJitterMs,
+			)
+			time.Sleep(delay)
+			continue
+		}
+
+		return totalRowsRead, err
+	}
+}

internal/app/etl/extractors/process.go

@@ -0,0 +1,127 @@
+package extractors
+
+import (
+	"context"
+	"fmt"
+
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/convert"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/custom_errors"
+	dbwrapper "git.ksdemosapps.com/kylesoda/go-migrate/internal/app/db-wrapper"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/models"
+	// "github.com/sirupsen/logrus"
+)
+
+func errorFromLastPartitionRow(
+	lastRow models.UnknownRowValues,
+	indexPrimaryKey int,
+	partition models.Partition,
+	previousError error,
+) error {
+	lastIdRawValue := lastRow[indexPrimaryKey]
+
+	lastId, ok := convert.ToInt64(lastIdRawValue)
+	if !ok {
+		currentPartition := partition
+		currentPartition.RetryCounter = 3
+		return &custom_errors.ExtractorError{
+			Partition: currentPartition,
+			HasLastId: true,
+			Msg:       fmt.Sprintf("Couldn't cast last id value as int: %s", previousError.Error()),
+		}
+	}
+
+	return &custom_errors.ExtractorError{
+		Partition: partition,
+		HasLastId: true,
+		LastId:    lastId,
+		Msg:       previousError.Error(),
+	}
+}
+
+func (ex *GenericExtractor) ProcessPartition(
+	ctx context.Context,
+	tableInfo config.SourceTableInfo,
+	columns []models.ColumnType,
+	batchSize int,
+	partition models.Partition,
+	indexPrimaryKey int,
+	chBatchesOut chan<- models.Batch,
+	fromJsonColumns []config.FromJsonItem,
+) (int64, error) {
+	query := dbwrapper.ExtractionQuery{
+		Schema:     tableInfo.Schema,
+		Table:      tableInfo.Table,
+		PrimaryKey: tableInfo.PrimaryKey,
+		Columns:    columns,
+		LowerLimit: dbwrapper.ExtractorQueryLimit{
+			IsValid:     partition.HasRange && partition.Range.Min > 0,
+			IsInclusive: partition.Range.IsMinInclusive,
+			Value:       partition.Range.Min,
+		},
+		UpperLimit: dbwrapper.ExtractorQueryLimit{
+			IsValid:     partition.HasRange && partition.Range.Max > 0,
+			IsInclusive: partition.Range.IsMaxInclusive,
+			Value:       partition.Range.Max,
+		},
+		FromJsonColumns: fromJsonColumns,
+	}
+
+	// logrus.Debugf("Processing partition: %+v (%s.%s)", query, tableInfo.Schema, tableInfo.Table)
+	rows, err := ex.db.QueryFromObject(ctx, query)
+	if err != nil {
+		return 0, err
+	}
+	defer rows.Close()
+
+	batchRows := make([]models.UnknownRowValues, 0, batchSize)
+	var rowsRead int64 = 0
+	var lastRow models.UnknownRowValues
+
+	for rows.Next() {
+		rowValues := make([]any, len(columns))
+		scanArgs := make([]any, len(columns))
+
+		for i := range rowValues {
+			scanArgs[i] = &rowValues[i]
+		}
+
+		if err := rows.Scan(scanArgs...); err != nil {
+			if len(batchRows) == 0 {
+				return rowsRead, err
+			}
+
+			if err := flush(ctx, batchSize, batchRows, chBatchesOut); err != nil {
+				return rowsRead, err
+			}
+
+			lastRow := batchRows[len(batchRows)-1]
+			return rowsRead, errorFromLastPartitionRow(lastRow, indexPrimaryKey, partition, err)
+		}
+		rowsRead++
+		lastRow = rowValues
+
+		batchRows = append(batchRows, rowValues)
+		if len(batchRows) >= batchSize {
+			// logrus.Debugf("Batch size reached, flushing batch with %v rows (rowsRead=%v)", len(batchRows), rowsRead)
+			if err := flush(ctx, batchSize, batchRows, chBatchesOut); err != nil {
+				// logrus.Warnf("Error flushing rows: %v", err)
+				return rowsRead, err
+			}
+			batchRows = make([]models.UnknownRowValues, 0, batchSize)
+		}
+	}
+
+	if err := flush(ctx, batchSize, batchRows, chBatchesOut); err != nil {
+		return rowsRead, err
+	}
+
+	if err := rows.Err(); err != nil {
+		if lastRow != nil {
+			return rowsRead, errorFromLastPartitionRow(lastRow, indexPrimaryKey, partition, err)
+		}
+		return rowsRead, err
+	}
+
+	return rowsRead, nil
+}

internal/app/etl/loaders/consume.go

@@ -0,0 +1,153 @@
+package loaders
+
+import (
+	"context"
+	"errors"
+	"sync"
+	"sync/atomic"
+
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/custom_errors"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/models"
+	"github.com/google/uuid"
+	"github.com/sirupsen/logrus"
+)
+
+type loaderAccumulator struct {
+	batchSize   int
+	rows        []models.UnknownRowValues
+	parents     []models.BatchRef
+	pendingDone int
+}
+
+func (a *loaderAccumulator) add(batch models.Batch) {
+	a.rows = append(a.rows, batch.Rows...)
+	a.parents = append(a.parents, models.BatchRef{Id: batch.Id})
+	a.pendingDone++
+}
+
+func (a *loaderAccumulator) ready() bool {
+	return len(a.rows) >= a.batchSize
+}
+
+func (a *loaderAccumulator) drainPending(wg *sync.WaitGroup) {
+	for range a.pendingDone {
+		wg.Done()
+	}
+}
+
+func sendLoadError(
+	ctx context.Context,
+	err error,
+	retryConfig config.RetryConfig,
+	failedBatchesCount *int32,
+	chErrorsOut chan<- custom_errors.JobError,
+) bool {
+	atomic.AddInt32(failedBatchesCount, 1)
+
+	var jobErr custom_errors.JobError
+	if je, ok := errors.AsType[*custom_errors.JobError](err); ok {
+		jobErr = *je
+	} else {
+		jobErr = custom_errors.JobError{ShouldCancelJob: false, Msg: err.Error(), Prev: err}
+	}
+
+	select {
+	case <-ctx.Done():
+		return false
+	case chErrorsOut <- jobErr:
+	}
+
+	if atomic.LoadInt32(failedBatchesCount) > int32(retryConfig.MaxFailedBatchesLoad) {
+		select {
+		case <-ctx.Done():
+		case chErrorsOut <- custom_errors.JobError{ShouldCancelJob: true, Msg: "Max failed batches (load) reached"}:
+		}
+		return false
+	}
+
+	return true
+}
+
+func (gl *GenericLoader) Consume(
+	ctx context.Context,
+	tableInfo config.TargetTableInfo,
+	columns []models.ColumnType,
+	retryConfig config.RetryConfig,
+	batchSize int,
+	chBatchesIn <-chan models.Batch,
+	chErrorsOut chan<- custom_errors.JobError,
+	wgActiveBatches *sync.WaitGroup,
+	rowsLoaded *int64,
+	failedBatchesCount *int32,
+) {
+	colNames := mapSlice(columns, func(col models.ColumnType) string {
+		return col.Name()
+	})
+
+	acc := &loaderAccumulator{batchSize: batchSize}
+	defer acc.drainPending(wgActiveBatches)
+
+	flush := func() bool {
+		if len(acc.rows) == 0 {
+			return true
+		}
+		count := len(acc.parents)
+		superBatch := models.Batch{
+			Id:            uuid.New(),
+			ParentBatches: acc.parents,
+			Rows:          acc.rows,
+		}
+		processedRows, err := gl.ProcessBatchWithRetries(ctx, tableInfo, colNames, retryConfig, superBatch)
+		for range count {
+			wgActiveBatches.Done()
+		}
+		acc.pendingDone -= count
+		acc.rows = nil
+		acc.parents = nil
+
+		if err != nil {
+			return sendLoadError(ctx, err, retryConfig, failedBatchesCount, chErrorsOut)
+		}
+
+		current := atomic.LoadInt64(rowsLoaded)
+		logrus.Debugf("Rows loaded (batch loaded): +%v [current=%v] (%s.%s)", processedRows, current, tableInfo.Schema, tableInfo.Table)
+		atomic.AddInt64(rowsLoaded, int64(processedRows))
+		return true
+	}
+
+	for {
+		select {
+		case <-ctx.Done():
+			return
+
+		case batch, ok := <-chBatchesIn:
+			if !ok {
+				flush()
+				return
+			}
+
+			if batchSize <= 0 {
+				processedRows, err := gl.ProcessBatchWithRetries(ctx, tableInfo, colNames, retryConfig, batch)
+				wgActiveBatches.Done()
+				if err != nil {
+					if !sendLoadError(ctx, err, retryConfig, failedBatchesCount, chErrorsOut) {
+						return
+					}
+					continue
+				}
+				current := atomic.LoadInt64(rowsLoaded)
+				logrus.Debugf("Rows loaded: +%v [current=%v] (%s.%s)", processedRows, current, tableInfo.Schema, tableInfo.Table)
+				atomic.AddInt64(rowsLoaded, int64(processedRows))
+				continue
+			}
+
+			acc.add(batch)
+			if acc.ready() {
+				if !flush() {
+					return
+				}
+			}
+		}
+	}
+}

internal/app/etl/loaders/consume_test.go

@@ -0,0 +1,603 @@
+package loaders
+
+import (
+	"context"
+	"errors"
+	"sync"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/custom_errors"
+	dbwrapper "git.ksdemosapps.com/kylesoda/go-migrate/internal/app/db-wrapper"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/models"
+	"github.com/google/uuid"
+)
+
+const testTimeout = 2 * time.Second
+
+type mockResult struct {
+	err error
+}
+
+type mockDbWrapper struct {
+	mu        sync.Mutex
+	callCount int
+	results   []mockResult
+}
+
+func newMockDb(results ...mockResult) *mockDbWrapper {
+	return &mockDbWrapper{results: results}
+}
+
+func (m *mockDbWrapper) SaveMassive(_ context.Context, _ string, _ string, _ []string, rows [][]any) (int64, error) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	idx := m.callCount
+	m.callCount++
+	if idx < len(m.results) && m.results[idx].err != nil {
+		return 0, m.results[idx].err
+	}
+	return int64(len(rows)), nil
+}
+
+func (m *mockDbWrapper) Close() error                              { return nil }
+func (m *mockDbWrapper) Connect(_ context.Context, _ string) error { return nil }
+func (m *mockDbWrapper) Exec(_ context.Context, _ string, _ ...any) (dbwrapper.ExecResult, error) {
+	return dbwrapper.ExecResult{}, nil
+}
+func (m *mockDbWrapper) GetDialect() string { return "" }
+func (m *mockDbWrapper) Query(_ context.Context, _ string, _ ...any) (dbwrapper.RowsResult, error) {
+	return nil, nil
+}
+func (m *mockDbWrapper) QueryRow(_ context.Context, _ string, _ ...any) dbwrapper.RowResult {
+	return nil
+}
+func (m *mockDbWrapper) QueryFromObject(_ context.Context, _ dbwrapper.ExtractionQuery) (dbwrapper.RowsResult, error) {
+	return nil, nil
+}
+
+func makeBatch(numRows int) models.Batch {
+	rows := make([]models.UnknownRowValues, numRows)
+	for i := range rows {
+		rows[i] = models.UnknownRowValues{i}
+	}
+	return models.Batch{Id: uuid.New(), Rows: rows}
+}
+
+func newLoader(db *mockDbWrapper) GenericLoader {
+	return GenericLoader{db: db}
+}
+
+func rc(maxFailed int) config.RetryConfig {
+	return config.RetryConfig{Attempts: 1, MaxFailedBatchesLoad: maxFailed}
+}
+
+func sendBatch(chIn chan<- models.Batch, batch models.Batch, wg *sync.WaitGroup) {
+	wg.Add(1)
+	chIn <- batch
+}
+
+func runConsume(
+	ctx context.Context,
+	gl GenericLoader,
+	retryConfig config.RetryConfig,
+	batchSize int,
+	chIn <-chan models.Batch,
+	chErr chan<- custom_errors.JobError,
+	wg *sync.WaitGroup,
+	rowsLoaded *int64,
+	failedCount *int32,
+) <-chan struct{} {
+	done := make(chan struct{})
+	go func() {
+		gl.Consume(ctx, config.TargetTableInfo{}, nil, retryConfig, batchSize,
+			chIn, chErr, wg, rowsLoaded, failedCount)
+		close(done)
+	}()
+	return done
+}
+
+func waitWg(wg *sync.WaitGroup) <-chan struct{} {
+	done := make(chan struct{})
+	go func() { wg.Wait(); close(done) }()
+	return done
+}
+
+func dbError() error { return errors.New("connection reset by peer") }
+
+func TestLoaderAccumulator_Add(t *testing.T) {
+	acc := &loaderAccumulator{batchSize: 5}
+	b1 := makeBatch(2)
+	b2 := makeBatch(3)
+
+	acc.add(b1)
+	acc.add(b2)
+
+	if len(acc.rows) != 5 {
+		t.Errorf("expected 5 rows, got %d", len(acc.rows))
+	}
+	if len(acc.parents) != 2 {
+		t.Fatalf("expected 2 parents, got %d", len(acc.parents))
+	}
+	if acc.parents[0].Id != b1.Id || acc.parents[1].Id != b2.Id {
+		t.Error("parent IDs do not match source batch IDs in order")
+	}
+	if acc.pendingDone != 2 {
+		t.Errorf("expected pendingDone=2, got %d", acc.pendingDone)
+	}
+}
+
+func TestLoaderAccumulator_Ready(t *testing.T) {
+	acc := &loaderAccumulator{batchSize: 3}
+	acc.add(makeBatch(2))
+	if acc.ready() {
+		t.Error("should not be ready with 2 rows and batchSize=3")
+	}
+	acc.add(makeBatch(1))
+	if !acc.ready() {
+		t.Error("should be ready with 3 rows and batchSize=3")
+	}
+}
+
+func TestLoaderAccumulator_DrainPending_ReleasesWg(t *testing.T) {
+	acc := &loaderAccumulator{batchSize: 5, pendingDone: 3}
+	var wg sync.WaitGroup
+	wg.Add(3)
+
+	acc.drainPending(&wg)
+
+	select {
+	case <-waitWg(&wg):
+	case <-time.After(testTimeout):
+		t.Fatal("wg.Wait() timed out: drainPending did not call Done() enough times")
+	}
+}
+
+func TestLoaderAccumulator_DrainPending_ZeroPending(t *testing.T) {
+	acc := &loaderAccumulator{batchSize: 5, pendingDone: 0}
+	var wg sync.WaitGroup
+
+	acc.drainPending(&wg)
+
+	select {
+	case <-waitWg(&wg):
+	case <-time.After(testTimeout):
+		t.Fatal("wg.Wait() timed out")
+	}
+}
+
+func TestSendLoadError_PlainError_WrappedAsNonFatal(t *testing.T) {
+	ch := make(chan custom_errors.JobError, 2)
+	var failedCount int32
+
+	result := sendLoadError(context.Background(), errors.New("db error"), rc(10), &failedCount, ch)
+
+	if !result {
+		t.Error("expected true (below threshold)")
+	}
+	if atomic.LoadInt32(&failedCount) != 1 {
+		t.Errorf("expected failedCount=1, got %d", failedCount)
+	}
+	select {
+	case e := <-ch:
+		if e.ShouldCancelJob {
+			t.Error("plain error should be wrapped as ShouldCancelJob=false")
+		}
+	default:
+		t.Error("expected an error in the channel")
+	}
+}
+
+func TestSendLoadError_JobError_PassesThrough(t *testing.T) {
+	ch := make(chan custom_errors.JobError, 2)
+	var failedCount int32
+	original := &custom_errors.JobError{ShouldCancelJob: false, Msg: "custom msg"}
+
+	sendLoadError(context.Background(), original, rc(10), &failedCount, ch)
+
+	select {
+	case e := <-ch:
+		if e.Msg != "custom msg" || e.ShouldCancelJob {
+			t.Errorf("JobError should pass through unchanged, got %+v", e)
+		}
+	default:
+		t.Error("expected an error in the channel")
+	}
+}
+
+func TestSendLoadError_FatalJobError_BelowThreshold_ReturnsTrue(t *testing.T) {
+	ch := make(chan custom_errors.JobError, 2)
+	var failedCount int32
+	fatal := &custom_errors.JobError{ShouldCancelJob: true, Msg: "unique constraint"}
+
+	result := sendLoadError(context.Background(), fatal, rc(10), &failedCount, ch)
+
+	if !result {
+		t.Error("below-threshold fatal error should return true (external cancel expected from JobErrorHandler)")
+	}
+	select {
+	case e := <-ch:
+		if !e.ShouldCancelJob {
+			t.Error("fatal JobError should be forwarded with ShouldCancelJob=true")
+		}
+	default:
+		t.Error("expected the fatal error in the channel")
+	}
+}
+
+func TestSendLoadError_ThresholdExceeded_ReturnsFalse(t *testing.T) {
+	ch := make(chan custom_errors.JobError, 2)
+	var failedCount int32
+
+	result := sendLoadError(context.Background(), errors.New("db error"), rc(0), &failedCount, ch)
+
+	if result {
+		t.Error("expected false when threshold exceeded")
+	}
+	if len(ch) != 2 {
+		t.Fatalf("expected 2 errors (batch error + fatal threshold error), got %d", len(ch))
+	}
+	<-ch // batch error
+	threshold := <-ch
+	if !threshold.ShouldCancelJob {
+		t.Error("second error should be the fatal threshold error (ShouldCancelJob=true)")
+	}
+}
+
+func TestSendLoadError_AtThresholdBoundary(t *testing.T) {
+	ch := make(chan custom_errors.JobError, 6)
+	var failedCount int32
+
+	if !sendLoadError(context.Background(), errors.New("err"), rc(2), &failedCount, ch) {
+		t.Error("first failure: expected true (below threshold)")
+	}
+	if !sendLoadError(context.Background(), errors.New("err"), rc(2), &failedCount, ch) {
+		t.Error("second failure: expected true (at threshold, not exceeded)")
+	}
+	if sendLoadError(context.Background(), errors.New("err"), rc(2), &failedCount, ch) {
+		t.Error("third failure: expected false (threshold exceeded)")
+	}
+}
+
+func TestSendLoadError_ContextCancelled_ReturnsFalse(t *testing.T) {
+	ch := make(chan custom_errors.JobError)
+	var failedCount int32
+
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel()
+
+	result := sendLoadError(ctx, errors.New("db error"), rc(10), &failedCount, ch)
+
+	if result {
+		t.Error("expected false when context is cancelled")
+	}
+	if len(ch) != 0 {
+		t.Error("no error should be sent when context is cancelled")
+	}
+}
+
+func TestConsume_Passthrough_RowsLoaded(t *testing.T) {
+	db := newMockDb()
+	gl := newLoader(db)
+	chIn := make(chan models.Batch, 1)
+	chErr := make(chan custom_errors.JobError, 1)
+	var wg sync.WaitGroup
+	var rowsLoaded int64
+	var failedCount int32
+
+	sendBatch(chIn, makeBatch(5), &wg)
+	close(chIn)
+
+	<-runConsume(context.Background(), gl, rc(0), 0, chIn, chErr, &wg, &rowsLoaded, &failedCount)
+	wg.Wait()
+
+	if rowsLoaded != 5 {
+		t.Errorf("expected rowsLoaded=5, got %d", rowsLoaded)
+	}
+	if db.callCount != 1 {
+		t.Errorf("expected 1 SaveMassive call, got %d", db.callCount)
+	}
+}
+
+func TestConsume_Passthrough_MultipleBatches_RowsAccumulate(t *testing.T) {
+	db := newMockDb()
+	gl := newLoader(db)
+	chIn := make(chan models.Batch, 3)
+	chErr := make(chan custom_errors.JobError, 1)
+	var wg sync.WaitGroup
+	var rowsLoaded int64
+	var failedCount int32
+
+	sendBatch(chIn, makeBatch(3), &wg)
+	sendBatch(chIn, makeBatch(2), &wg)
+	sendBatch(chIn, makeBatch(4), &wg)
+	close(chIn)
+
+	<-runConsume(context.Background(), gl, rc(10), 0, chIn, chErr, &wg, &rowsLoaded, &failedCount)
+	wg.Wait()
+
+	if rowsLoaded != 9 {
+		t.Errorf("expected rowsLoaded=9, got %d", rowsLoaded)
+	}
+}
+
+func TestConsume_Passthrough_WgDoneBeforeErrorHandling(t *testing.T) {
+	db := newMockDb(mockResult{err: dbError()})
+	gl := newLoader(db)
+	chIn := make(chan models.Batch, 1)
+	chErr := make(chan custom_errors.JobError, 2)
+	var wg sync.WaitGroup
+	var rowsLoaded int64
+	var failedCount int32
+
+	sendBatch(chIn, makeBatch(2), &wg)
+	close(chIn)
+
+	<-runConsume(context.Background(), gl, rc(10), 0, chIn, chErr, &wg, &rowsLoaded, &failedCount)
+
+	select {
+	case <-waitWg(&wg):
+	case <-time.After(testTimeout):
+		t.Fatal("wg.Wait() timed out: Done() was not called even though processing failed")
+	}
+}
+
+func TestConsume_Passthrough_NonFatalError_Continues(t *testing.T) {
+	db := newMockDb(mockResult{err: dbError()})
+	gl := newLoader(db)
+	chIn := make(chan models.Batch, 2)
+	chErr := make(chan custom_errors.JobError, 3)
+	var wg sync.WaitGroup
+	var rowsLoaded int64
+	var failedCount int32
+
+	sendBatch(chIn, makeBatch(2), &wg)
+	sendBatch(chIn, makeBatch(3), &wg)
+	close(chIn)
+
+	<-runConsume(context.Background(), gl, rc(10), 0, chIn, chErr, &wg, &rowsLoaded, &failedCount)
+	wg.Wait()
+
+	if rowsLoaded != 3 {
+		t.Errorf("expected rowsLoaded=3 (only second batch succeeded), got %d", rowsLoaded)
+	}
+	if atomic.LoadInt32(&failedCount) != 1 {
+		t.Errorf("expected failedCount=1, got %d", failedCount)
+	}
+	if len(chErr) == 0 {
+		t.Error("expected at least one error in chErr for the failed batch")
+	}
+}
+
+func TestConsume_Passthrough_ThresholdExceeded_Exits(t *testing.T) {
+	db := newMockDb(mockResult{err: dbError()})
+	gl := newLoader(db)
+	chIn := make(chan models.Batch, 1)
+	chErr := make(chan custom_errors.JobError, 3)
+	var wg sync.WaitGroup
+	var rowsLoaded int64
+	var failedCount int32
+
+	sendBatch(chIn, makeBatch(1), &wg)
+
+	done := runConsume(context.Background(), gl, rc(0), 0, chIn, chErr, &wg, &rowsLoaded, &failedCount)
+
+	select {
+	case <-done:
+	case <-time.After(testTimeout):
+		t.Fatal("Consume did not exit after threshold exceeded")
+	}
+
+	select {
+	case <-waitWg(&wg):
+	case <-time.After(testTimeout):
+		t.Fatal("wg.Wait() timed out after threshold exit")
+	}
+}
+
+func TestConsume_Accumulation_FlushOnThreshold(t *testing.T) {
+	db := newMockDb()
+	gl := newLoader(db)
+	chIn := make(chan models.Batch, 3)
+	chErr := make(chan custom_errors.JobError, 1)
+	var wg sync.WaitGroup
+	var rowsLoaded int64
+	var failedCount int32
+
+	sendBatch(chIn, makeBatch(1), &wg)
+	sendBatch(chIn, makeBatch(1), &wg)
+	sendBatch(chIn, makeBatch(1), &wg)
+	close(chIn)
+
+	<-runConsume(context.Background(), gl, rc(0), 3, chIn, chErr, &wg, &rowsLoaded, &failedCount)
+	wg.Wait()
+
+	if rowsLoaded != 3 {
+		t.Errorf("expected rowsLoaded=3, got %d", rowsLoaded)
+	}
+	if db.callCount != 1 {
+		t.Errorf("expected 1 SaveMassive call, got %d", db.callCount)
+	}
+}
+
+func TestConsume_Accumulation_FlushOnClose(t *testing.T) {
+	db := newMockDb()
+	gl := newLoader(db)
+	chIn := make(chan models.Batch, 2)
+	chErr := make(chan custom_errors.JobError, 1)
+	var wg sync.WaitGroup
+	var rowsLoaded int64
+	var failedCount int32
+
+	sendBatch(chIn, makeBatch(2), &wg)
+	sendBatch(chIn, makeBatch(3), &wg)
+	close(chIn)
+
+	<-runConsume(context.Background(), gl, rc(0), 10, chIn, chErr, &wg, &rowsLoaded, &failedCount)
+	wg.Wait()
+
+	if rowsLoaded != 5 {
+		t.Errorf("expected rowsLoaded=5, got %d", rowsLoaded)
+	}
+	if db.callCount != 1 {
+		t.Errorf("expected exactly 1 SaveMassive call (single flush on close), got %d", db.callCount)
+	}
+}
+
+func TestConsume_Accumulation_RowsLoadedCorrect(t *testing.T) {
+	db := newMockDb()
+	gl := newLoader(db)
+	chIn := make(chan models.Batch, 5)
+	chErr := make(chan custom_errors.JobError, 1)
+	var wg sync.WaitGroup
+	var rowsLoaded int64
+	var failedCount int32
+
+	for range 5 {
+		sendBatch(chIn, makeBatch(2), &wg)
+	}
+	close(chIn)
+
+	<-runConsume(context.Background(), gl, rc(0), 4, chIn, chErr, &wg, &rowsLoaded, &failedCount)
+	wg.Wait()
+
+	if rowsLoaded != 10 {
+		t.Errorf("expected rowsLoaded=10, got %d", rowsLoaded)
+	}
+	if db.callCount != 3 {
+		t.Errorf("expected 3 SaveMassive calls (2 threshold flushes + 1 on close), got %d", db.callCount)
+	}
+}
+
+func TestConsume_Accumulation_WgBalanced_OnContextCancel(t *testing.T) {
+	db := newMockDb()
+	gl := newLoader(db)
+	chIn := make(chan models.Batch)
+	chErr := make(chan custom_errors.JobError, 1)
+	var wg sync.WaitGroup
+	var rowsLoaded int64
+	var failedCount int32
+
+	ctx, cancel := context.WithCancel(context.Background())
+	done := runConsume(ctx, gl, rc(0), 10, chIn, chErr, &wg, &rowsLoaded, &failedCount)
+
+	sendBatch(chIn, makeBatch(1), &wg)
+	sendBatch(chIn, makeBatch(1), &wg)
+	cancel()
+
+	select {
+	case <-done:
+	case <-time.After(testTimeout):
+		t.Fatal("Consume did not exit after context cancellation")
+	}
+
+	select {
+	case <-waitWg(&wg):
+	case <-time.After(testTimeout):
+		t.Fatal("wg.Wait() timed out: drainPending did not release accumulated batches on cancel")
+	}
+}
+
+func TestConsume_Accumulation_ErrorInFlush_WgStillBalanced(t *testing.T) {
+	db := newMockDb(mockResult{err: dbError()})
+	gl := newLoader(db)
+	chIn := make(chan models.Batch, 2)
+	chErr := make(chan custom_errors.JobError, 3)
+	var wg sync.WaitGroup
+	var rowsLoaded int64
+	var failedCount int32
+
+	sendBatch(chIn, makeBatch(1), &wg)
+	sendBatch(chIn, makeBatch(1), &wg)
+	close(chIn)
+
+	<-runConsume(context.Background(), gl, rc(10), 2, chIn, chErr, &wg, &rowsLoaded, &failedCount)
+
+	select {
+	case <-waitWg(&wg):
+	case <-time.After(testTimeout):
+		t.Fatal("wg.Wait() timed out: wg.Done() not called after flush error")
+	}
+}
+
+func TestConsume_Accumulation_MultipleFlushes_NonFatalErrors(t *testing.T) {
+	db := newMockDb(mockResult{err: dbError()}, mockResult{err: dbError()})
+	gl := newLoader(db)
+	chIn := make(chan models.Batch, 4)
+	chErr := make(chan custom_errors.JobError, 6)
+	var wg sync.WaitGroup
+	var rowsLoaded int64
+	var failedCount int32
+
+	for range 4 {
+		sendBatch(chIn, makeBatch(1), &wg)
+	}
+	close(chIn)
+
+	<-runConsume(context.Background(), gl, rc(10), 2, chIn, chErr, &wg, &rowsLoaded, &failedCount)
+
+	select {
+	case <-waitWg(&wg):
+	case <-time.After(testTimeout):
+		t.Fatal("wg.Wait() timed out")
+	}
+
+	if atomic.LoadInt32(&failedCount) != 2 {
+		t.Errorf("expected failedCount=2, got %d", failedCount)
+	}
+	if rowsLoaded != 0 {
+		t.Errorf("expected rowsLoaded=0 (all batches failed), got %d", rowsLoaded)
+	}
+}
+
+func TestConsume_EmptyInput_NoProcessing(t *testing.T) {
+	db := newMockDb()
+	gl := newLoader(db)
+	chIn := make(chan models.Batch)
+	chErr := make(chan custom_errors.JobError, 1)
+	var wg sync.WaitGroup
+	var rowsLoaded int64
+	var failedCount int32
+
+	close(chIn)
+
+	done := runConsume(context.Background(), gl, rc(0), 5, chIn, chErr, &wg, &rowsLoaded, &failedCount)
+
+	select {
+	case <-done:
+	case <-time.After(testTimeout):
+		t.Fatal("Consume did not exit after empty input channel was closed")
+	}
+
+	if db.callCount != 0 {
+		t.Errorf("expected no SaveMassive calls, got %d", db.callCount)
+	}
+	if rowsLoaded != 0 {
+		t.Errorf("expected rowsLoaded=0, got %d", rowsLoaded)
+	}
+	wg.Wait()
+}
+
+func TestConsume_ContextCancellation_Exits(t *testing.T) {
+	db := newMockDb()
+	gl := newLoader(db)
+	chIn := make(chan models.Batch)
+	chErr := make(chan custom_errors.JobError, 1)
+	var wg sync.WaitGroup
+	var rowsLoaded int64
+	var failedCount int32
+
+	ctx, cancel := context.WithCancel(context.Background())
+	done := runConsume(ctx, gl, rc(0), 0, chIn, chErr, &wg, &rowsLoaded, &failedCount)
+
+	cancel()
+
+	select {
+	case <-done:
+	case <-time.After(testTimeout):
+		t.Fatal("Consume did not exit after context cancellation")
+	}
+	wg.Wait()
+}

internal/app/etl/loaders/main.go

@@ -0,0 +1,13 @@
+package loaders
+
+import (
+	dbwrapper "git.ksdemosapps.com/kylesoda/go-migrate/internal/app/db-wrapper"
+)
+
+type GenericLoader struct {
+	db dbwrapper.DbWrapper
+}
+
+func NewGenericLoader(db dbwrapper.DbWrapper) GenericLoader {
+	return GenericLoader{db: db}
+}

internal/app/etl/loaders/process-with-retries.go

@@ -0,0 +1,49 @@
+package loaders
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"time"
+
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/custom_errors"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/models"
+)
+
+func (gl *GenericLoader) ProcessBatchWithRetries(
+	ctx context.Context,
+	tableInfo config.TargetTableInfo,
+	colNames []string,
+	retryConfig config.RetryConfig,
+	batch models.Batch,
+) (int64, error) {
+	for {
+		rowsLoaded, err := gl.ProcessBatch(ctx, tableInfo, colNames, batch)
+		if err == nil {
+			return rowsLoaded, nil
+		}
+
+		if btError, ok := errors.AsType[*custom_errors.LoaderError](err); ok {
+			batch.RetryCounter++
+
+			if batch.RetryCounter >= retryConfig.Attempts {
+				return rowsLoaded, &custom_errors.JobError{
+					Msg:  fmt.Sprintf("Batch %v reached max retries (%d)", batch.Id, batch.RetryCounter),
+					Prev: btError,
+				}
+			}
+
+			delay := custom_errors.ComputeBackoffDelay(
+				batch.RetryCounter,
+				retryConfig.BaseDelayMs,
+				retryConfig.MaxDelayMs,
+				retryConfig.MaxJitterMs,
+			)
+			time.Sleep(delay)
+			continue
+		}
+
+		return rowsLoaded, err
+	}
+}

internal/app/etl/loaders/process.go

@@ -0,0 +1,43 @@
+package loaders
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/custom_errors"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/models"
+	"github.com/jackc/pgx/v5/pgconn"
+)
+
+func (gl *GenericLoader) ProcessBatch(
+	ctx context.Context,
+	tableInfo config.TargetTableInfo,
+	colNames []string,
+	batch models.Batch,
+) (int64, error) {
+	_, err := gl.db.SaveMassive(
+		ctx,
+		tableInfo.Schema,
+		tableInfo.Table,
+		colNames,
+		batch.Rows,
+	)
+
+	if err != nil {
+		if pgErr, ok := errors.AsType[*pgconn.PgError](err); ok {
+			if pgErr.Code == "23505" {
+				return 0, &custom_errors.JobError{
+					ShouldCancelJob: true,
+					Msg:             fmt.Sprintf("Fatal error in table %s.%s", tableInfo.Schema, tableInfo.Table),
+					Prev:            err,
+				}
+			}
+		}
+
+		return 0, &custom_errors.LoaderError{Batch: batch, Msg: err.Error()}
+	}
+
+	return int64(len(batch.Rows)), nil
+}

internal/app/etl/loaders/utils.go

@@ -0,0 +1,11 @@
+package loaders
+
+func mapSlice[T any, V any](input []T, mapper func(T) V) []V {
+	result := make([]V, len(input))
+
+	for i, v := range input {
+		result[i] = mapper(v)
+	}
+
+	return result
+}

internal/app/etl/table_analyzers/main.go

@@ -0,0 +1,133 @@
+package table_analyzers
+
+import (
+	"context"
+	"math"
+
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/etl"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/models"
+	"github.com/google/uuid"
+	"github.com/sirupsen/logrus"
+)
+
+func PartitionRangeGenerator(
+	ctx context.Context,
+	tableAnalyzer etl.TableAnalyzer,
+	tableInfo config.TableInfo,
+	partitionColumn string,
+	partitionCalculationStrategy string,
+	rowsPerPartition int64,
+	jobRange config.RangeConfig,
+) ([]models.Partition, error) {
+	rowsCount, err := tableAnalyzer.EstimateTotalRows(ctx, tableInfo)
+	logrus.Infof("Estimated rows in source: %v (%s.%s)", rowsCount, tableInfo.Schema, tableInfo.Table)
+	if err != nil {
+		return nil, err
+	}
+
+	if rowsCount <= rowsPerPartition {
+		hasRange := jobRange.Min != nil || jobRange.Max != nil
+		partition := models.Partition{Id: uuid.New(), HasRange: hasRange, RetryCounter: 0}
+		if hasRange {
+			var min, max int64
+			if jobRange.Min != nil {
+				min = *jobRange.Min
+			}
+			if jobRange.Max != nil {
+				max = *jobRange.Max
+			}
+			partition.Range = models.PartitionRange{
+				Min:            min,
+				Max:            max,
+				IsMinInclusive: jobRange.IsMinInclusive,
+				IsMaxInclusive: jobRange.IsMaxInclusive,
+			}
+		}
+		return []models.Partition{partition}, nil
+	}
+
+	partitionsCount := rowsCount / rowsPerPartition
+
+	if partitionCalculationStrategy == "ESTIMATION" {
+		return calculatePartitionsEstimation(ctx, tableAnalyzer, tableInfo, partitionColumn, partitionsCount, jobRange)
+	}
+
+	partitions, err := tableAnalyzer.CalculatePartitionRanges(ctx, tableInfo, partitionColumn, partitionsCount, jobRange)
+	if err != nil {
+		return nil, err
+	}
+
+	logrus.Debugf("Partitions count: %v (%s.%s)", len(partitions), tableInfo.Schema, tableInfo.Table)
+
+	return partitions, nil
+}
+
+func calculatePartitionsEstimation(
+	ctx context.Context,
+	tableAnalyzer etl.TableAnalyzer,
+	tableInfo config.TableInfo,
+	partitionColumn string,
+	partitionsCount int64,
+	rangeConstraint config.RangeConfig,
+) ([]models.Partition, error) {
+	var minValue, maxValue int64
+
+	if rangeConstraint.Min != nil && rangeConstraint.Max != nil {
+		minValue = *rangeConstraint.Min
+		maxValue = *rangeConstraint.Max
+		logrus.Infof("Column range for %s.%s.%s: [%d, %d] (user-defined)", tableInfo.Schema, tableInfo.Table, partitionColumn, minValue, maxValue)
+	} else if rangeConstraint.Min != nil || rangeConstraint.Max != nil {
+		result, err := tableAnalyzer.QueryMaxMinFromColumn(ctx, tableInfo, partitionColumn)
+		if err != nil {
+			return nil, err
+		}
+		if rangeConstraint.Min != nil {
+			minValue = *rangeConstraint.Min
+			maxValue = result.Max
+			logrus.Infof("Column range for %s.%s.%s: [%d, %d] (min user-defined)", tableInfo.Schema, tableInfo.Table, partitionColumn, minValue, maxValue)
+		} else {
+			minValue = result.Min
+			maxValue = *rangeConstraint.Max
+			logrus.Infof("Column range for %s.%s.%s: [%d, %d] (max user-defined)", tableInfo.Schema, tableInfo.Table, partitionColumn, minValue, maxValue)
+		}
+	} else {
+		result, err := tableAnalyzer.QueryMaxMinFromColumn(ctx, tableInfo, partitionColumn)
+		if err != nil {
+			return nil, err
+		}
+		logrus.Infof("Column range for %s.%s.%s: [%d, %d]", tableInfo.Schema, tableInfo.Table, partitionColumn, result.Min, result.Max)
+		minValue = result.Min
+		maxValue = result.Max
+	}
+	rangeSize := maxValue - minValue
+	stepSize := int64(math.Ceil(float64(rangeSize) / float64(partitionsCount)))
+
+	partitions := make([]models.Partition, 0, partitionsCount)
+
+	for i := range partitionsCount {
+		partitionMin := minValue + (i * stepSize)
+		partitionMax := minValue + ((i + 1) * stepSize)
+
+		if i == partitionsCount-1 {
+			partitionMax = maxValue
+		}
+
+		isMinInclusive := i == 0
+		partition := models.Partition{
+			Id:           uuid.New(),
+			HasRange:     true,
+			RetryCounter: 0,
+			Range: models.PartitionRange{
+				Min:            partitionMin,
+				Max:            partitionMax,
+				IsMinInclusive: isMinInclusive,
+				IsMaxInclusive: true,
+			},
+		}
+
+		partitions = append(partitions, partition)
+	}
+
+	return partitions, nil
+}

internal/app/etl/table_analyzers/main_test.go

@@ -0,0 +1,332 @@
+package table_analyzers
+
+import (
+	"context"
+	"testing"
+
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/etl"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/models"
+)
+
+type MockTableAnalyzer struct {
+	minValue  int64
+	maxValue  int64
+	totalRows int64
+	capturedRangeConstraint config.RangeConfig
+}
+
+func (m *MockTableAnalyzer) QueryColumnTypes(_ context.Context, _ config.TableInfo) ([]models.ColumnType, error) {
+	return nil, nil
+}
+
+func (m *MockTableAnalyzer) EstimateTotalRows(_ context.Context, _ config.TableInfo) (int64, error) {
+	return m.totalRows, nil
+}
+
+func (m *MockTableAnalyzer) QueryMaxMinFromColumn(_ context.Context, _ config.TableInfo, _ string) (etl.MaxMinColumnResult, error) {
+	return etl.MaxMinColumnResult{Min: m.minValue, Max: m.maxValue}, nil
+}
+
+func (m *MockTableAnalyzer) CalculatePartitionRanges(_ context.Context, _ config.TableInfo, _ string, _ int64, rangeConstraint config.RangeConfig) ([]models.Partition, error) {
+	m.capturedRangeConstraint = rangeConstraint
+	return []models.Partition{}, nil
+}
+
+//go:fix inline
+func ptr64(v int64) *int64 { return new(v) }
+
+var testTableInfo = config.TableInfo{Schema: "dbo", Table: "test"}
+
+func TestCalculatePartitionsEstimation_NoOverlap(t *testing.T) {
+	ctx := context.Background()
+	mock := &MockTableAnalyzer{minValue: 0, maxValue: 100}
+
+	partitions, err := calculatePartitionsEstimation(ctx, mock, testTableInfo, "id", 4, config.RangeConfig{})
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	if len(partitions) != 4 {
+		t.Errorf("expected 4 partitions, got %d", len(partitions))
+	}
+
+	for i := 0; i < len(partitions)-1; i++ {
+		current := partitions[i].Range
+		next := partitions[i+1].Range
+		if current.Max == next.Min && current.IsMaxInclusive && next.IsMinInclusive {
+			t.Errorf("partition %d and %d overlap at value %d (both inclusive)", i, i+1, current.Max)
+		}
+	}
+}
+
+func TestCalculatePartitionsEstimation_CoverageComplete(t *testing.T) {
+	ctx := context.Background()
+	mock := &MockTableAnalyzer{minValue: 1000, maxValue: 2000}
+
+	partitions, err := calculatePartitionsEstimation(ctx, mock, testTableInfo, "id", 5, config.RangeConfig{})
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	if partitions[0].Range.Min != 1000 || !partitions[0].Range.IsMinInclusive {
+		t.Errorf("first partition should start at 1000 (inclusive), got %d (inclusive=%v)",
+			partitions[0].Range.Min, partitions[0].Range.IsMinInclusive)
+	}
+
+	if partitions[len(partitions)-1].Range.Max != 2000 {
+		t.Errorf("last partition should end at 2000, got %d", partitions[len(partitions)-1].Range.Max)
+	}
+}
+
+func TestCalculatePartitionsEstimation_FirstPartitionInclusive(t *testing.T) {
+	ctx := context.Background()
+	mock := &MockTableAnalyzer{minValue: 50, maxValue: 70}
+
+	partitions, err := calculatePartitionsEstimation(ctx, mock, testTableInfo, "id", 3, config.RangeConfig{})
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	if !partitions[0].Range.IsMinInclusive {
+		t.Errorf("first partition should have IsMinInclusive=true")
+	}
+
+	if partitions[0].Range.Min != 50 {
+		t.Errorf("first partition should start at 50, got %d", partitions[0].Range.Min)
+	}
+
+	for i := 1; i < len(partitions); i++ {
+		if partitions[i].Range.IsMinInclusive {
+			t.Errorf("partition %d should have IsMinInclusive=false to avoid overlap", i)
+		}
+	}
+}
+
+func TestPartitionRangeGenerator_Exact_NoRange_PassesEmptyConstraint(t *testing.T) {
+	ctx := context.Background()
+	mock := &MockTableAnalyzer{totalRows: 1000}
+
+	_, err := PartitionRangeGenerator(ctx, mock, testTableInfo, "id", "EXACT", 100, config.RangeConfig{})
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	if mock.capturedRangeConstraint.Min != nil || mock.capturedRangeConstraint.Max != nil {
+		t.Errorf("expected empty range constraint, got min=%v max=%v",
+			mock.capturedRangeConstraint.Min, mock.capturedRangeConstraint.Max)
+	}
+}
+
+func TestPartitionRangeGenerator_Exact_BothBounds_PassesBothToAnalyzer(t *testing.T) {
+	ctx := context.Background()
+	mock := &MockTableAnalyzer{totalRows: 1000}
+	jobRange := config.RangeConfig{Min: ptr64(200), Max: ptr64(800), IsMinInclusive: true, IsMaxInclusive: true}
+
+	_, err := PartitionRangeGenerator(ctx, mock, testTableInfo, "id", "EXACT", 100, jobRange)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	rc := mock.capturedRangeConstraint
+	if rc.Min == nil || *rc.Min != 200 {
+		t.Errorf("expected Min=200, got %v", rc.Min)
+	}
+	if rc.Max == nil || *rc.Max != 800 {
+		t.Errorf("expected Max=800, got %v", rc.Max)
+	}
+	if !rc.IsMinInclusive || !rc.IsMaxInclusive {
+		t.Errorf("expected both bounds inclusive, got minInc=%v maxInc=%v", rc.IsMinInclusive, rc.IsMaxInclusive)
+	}
+}
+
+func TestPartitionRangeGenerator_Exact_MinOnly_PassesMinNilMax(t *testing.T) {
+	ctx := context.Background()
+	mock := &MockTableAnalyzer{totalRows: 1000}
+	jobRange := config.RangeConfig{Min: ptr64(500)}
+
+	_, err := PartitionRangeGenerator(ctx, mock, testTableInfo, "id", "EXACT", 100, jobRange)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	rc := mock.capturedRangeConstraint
+	if rc.Min == nil || *rc.Min != 500 {
+		t.Errorf("expected Min=500, got %v", rc.Min)
+	}
+	if rc.Max != nil {
+		t.Errorf("expected Max=nil (no upper bound), got %v", rc.Max)
+	}
+}
+
+func TestPartitionRangeGenerator_Exact_MaxOnly_PassesMaxNilMin(t *testing.T) {
+	ctx := context.Background()
+	mock := &MockTableAnalyzer{totalRows: 1000}
+	jobRange := config.RangeConfig{Max: ptr64(300)}
+
+	_, err := PartitionRangeGenerator(ctx, mock, testTableInfo, "id", "EXACT", 100, jobRange)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	rc := mock.capturedRangeConstraint
+	if rc.Min != nil {
+		t.Errorf("expected Min=nil (no lower bound), got %v", rc.Min)
+	}
+	if rc.Max == nil || *rc.Max != 300 {
+		t.Errorf("expected Max=300, got %v", rc.Max)
+	}
+}
+
+func TestPartitionRangeGenerator_Estimation_BothBounds_UsesUserRange(t *testing.T) {
+	ctx := context.Background()
+	// DB min/max differ intentionally — user bounds should take precedence.
+	mock := &MockTableAnalyzer{totalRows: 1000, minValue: 0, maxValue: 999}
+	jobRange := config.RangeConfig{Min: ptr64(200), Max: ptr64(700), IsMinInclusive: true}
+
+	partitions, err := PartitionRangeGenerator(ctx, mock, testTableInfo, "id", "ESTIMATION", 100, jobRange)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	if len(partitions) == 0 {
+		t.Fatal("expected at least one partition")
+	}
+
+	if partitions[0].Range.Min != 200 {
+		t.Errorf("first partition should start at user min=200, got %d", partitions[0].Range.Min)
+	}
+	if partitions[len(partitions)-1].Range.Max != 700 {
+		t.Errorf("last partition should end at user max=700, got %d", partitions[len(partitions)-1].Range.Max)
+	}
+}
+
+func TestPartitionRangeGenerator_Estimation_MinOnly_QueriesDBForMax(t *testing.T) {
+	ctx := context.Background()
+	mock := &MockTableAnalyzer{totalRows: 1000, minValue: 0, maxValue: 999}
+	jobRange := config.RangeConfig{Min: ptr64(500), IsMinInclusive: true}
+
+	partitions, err := PartitionRangeGenerator(ctx, mock, testTableInfo, "id", "ESTIMATION", 100, jobRange)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	if len(partitions) == 0 {
+		t.Fatal("expected at least one partition")
+	}
+
+	if partitions[0].Range.Min != 500 {
+		t.Errorf("first partition should start at user min=500, got %d", partitions[0].Range.Min)
+	}
+	if partitions[len(partitions)-1].Range.Max != 999 {
+		t.Errorf("last partition should end at DB max=999, got %d", partitions[len(partitions)-1].Range.Max)
+	}
+}
+
+func TestPartitionRangeGenerator_Estimation_MaxOnly_QueriesDBForMin(t *testing.T) {
+	ctx := context.Background()
+	mock := &MockTableAnalyzer{totalRows: 1000, minValue: 100, maxValue: 999}
+	jobRange := config.RangeConfig{Max: ptr64(600), IsMaxInclusive: true}
+
+	partitions, err := PartitionRangeGenerator(ctx, mock, testTableInfo, "id", "ESTIMATION", 100, jobRange)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	if len(partitions) == 0 {
+		t.Fatal("expected at least one partition")
+	}
+
+	if partitions[0].Range.Min != 100 {
+		t.Errorf("first partition should start at DB min=100, got %d", partitions[0].Range.Min)
+	}
+	if partitions[len(partitions)-1].Range.Max != 600 {
+		t.Errorf("last partition should end at user max=600, got %d", partitions[len(partitions)-1].Range.Max)
+	}
+}
+
+func TestPartitionRangeGenerator_SinglePartition_NoRange(t *testing.T) {
+	ctx := context.Background()
+	mock := &MockTableAnalyzer{totalRows: 50}
+
+	partitions, err := PartitionRangeGenerator(ctx, mock, testTableInfo, "id", "EXACT", 100, config.RangeConfig{})
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	if len(partitions) != 1 {
+		t.Fatalf("expected 1 partition, got %d", len(partitions))
+	}
+	if partitions[0].HasRange {
+		t.Error("single partition with no range should have HasRange=false")
+	}
+}
+
+func TestPartitionRangeGenerator_SinglePartition_BothBounds(t *testing.T) {
+	ctx := context.Background()
+	mock := &MockTableAnalyzer{totalRows: 50}
+	jobRange := config.RangeConfig{Min: ptr64(100), Max: ptr64(200), IsMinInclusive: true, IsMaxInclusive: true}
+
+	partitions, err := PartitionRangeGenerator(ctx, mock, testTableInfo, "id", "EXACT", 100, jobRange)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	if len(partitions) != 1 {
+		t.Fatalf("expected 1 partition, got %d", len(partitions))
+	}
+	p := partitions[0]
+	if !p.HasRange {
+		t.Error("expected HasRange=true")
+	}
+	if p.Range.Min != 100 || p.Range.Max != 200 {
+		t.Errorf("expected [100, 200], got [%d, %d]", p.Range.Min, p.Range.Max)
+	}
+	if !p.Range.IsMinInclusive || !p.Range.IsMaxInclusive {
+		t.Errorf("expected both inclusive, got minInc=%v maxInc=%v", p.Range.IsMinInclusive, p.Range.IsMaxInclusive)
+	}
+}
+
+func TestPartitionRangeGenerator_SinglePartition_MinOnly(t *testing.T) {
+	ctx := context.Background()
+	mock := &MockTableAnalyzer{totalRows: 50}
+	jobRange := config.RangeConfig{Min: ptr64(100), IsMinInclusive: true}
+
+	partitions, err := PartitionRangeGenerator(ctx, mock, testTableInfo, "id", "EXACT", 100, jobRange)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	p := partitions[0]
+	if !p.HasRange {
+		t.Error("expected HasRange=true")
+	}
+	if p.Range.Min != 100 {
+		t.Errorf("expected Min=100, got %d", p.Range.Min)
+	}
+	if p.Range.Max != 0 {
+		t.Errorf("expected Max=0 (no upper bound), got %d", p.Range.Max)
+	}
+}
+
+func TestPartitionRangeGenerator_SinglePartition_MaxOnly(t *testing.T) {
+	ctx := context.Background()
+	mock := &MockTableAnalyzer{totalRows: 50}
+	jobRange := config.RangeConfig{Max: ptr64(200), IsMaxInclusive: true}
+
+	partitions, err := PartitionRangeGenerator(ctx, mock, testTableInfo, "id", "EXACT", 100, jobRange)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	p := partitions[0]
+	if !p.HasRange {
+		t.Error("expected HasRange=true")
+	}
+	if p.Range.Min != 0 {
+		t.Errorf("expected Min=0 (no lower bound), got %d", p.Range.Min)
+	}
+	if p.Range.Max != 200 {
+		t.Errorf("expected Max=200, got %d", p.Range.Max)
+	}
+}

internal/app/etl/table_analyzers/mssql.go

@@ -0,0 +1,302 @@
+package table_analyzers
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+	"strings"
+	"time"
+
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
+	dbwrapper "git.ksdemosapps.com/kylesoda/go-migrate/internal/app/db-wrapper"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/etl"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/models"
+	"github.com/google/uuid"
+)
+
+type MssqlTableAnalyzer struct {
+	db dbwrapper.DbWrapper
+}
+
+func NewMssqlTableAnalyzer(db dbwrapper.DbWrapper) etl.TableAnalyzer {
+	return &MssqlTableAnalyzer{db: db}
+}
+
+const mssqlColumnMetadataQuery string = `
+SELECT 
+	c.name AS name,
+	t.name AS user_type,
+	CASE WHEN t.is_user_defined = 0 THEN t.name ELSE bt.name END AS system_type,
+	c.is_nullable AS nullable,
+	c.max_length AS max_length,
+	c.precision AS precision,
+	c.scale AS scale
+FROM sys.columns c
+JOIN sys.types t ON c.user_type_id = t.user_type_id
+LEFT JOIN sys.types bt ON t.is_user_defined = 1 AND bt.user_type_id = t.system_type_id
+JOIN sys.tables st ON c.object_id = st.object_id
+JOIN sys.schemas s ON st.schema_id = s.schema_id
+WHERE s.name = @schema AND st.name = @table AND (c.is_hidden = 0 OR (c.graph_type IS NOT NULL AND c.name LIKE '$%'))
+ORDER BY c.column_id;`
+
+type rawColumnMssql struct {
+	name       string
+	userType   string
+	systemType string
+	nullable   bool
+	maxLength  int64
+	precision  int64
+	scale      int64
+}
+
+func (ta *MssqlTableAnalyzer) systemTypeToUnifiedType(systemType string) string {
+	systemType = strings.ToLower(systemType)
+
+	if systemType == "varchar" || systemType == "char" || systemType == "nvarchar" || systemType == "nchar" || systemType == "text" || systemType == "ntext" {
+		return "STRING"
+	}
+
+	if systemType == "int" || systemType == "int4" || systemType == "integer" || systemType == "smallint" || systemType == "int2" || systemType == "bigint" || systemType == "int8" || systemType == "tinyint" {
+		return "INTEGER"
+	}
+
+	if systemType == "decimal" || systemType == "numeric" {
+		return "DECIMAL"
+	}
+
+	if systemType == "float" || systemType == "real" || systemType == "double precision" {
+		return "FLOAT"
+	}
+
+	if systemType == "bit" || systemType == "boolean" {
+		return "BOOLEAN"
+	}
+
+	if systemType == "date" {
+		return "DATE"
+	}
+	if systemType == "time" || systemType == "time without time zone" {
+		return "TIME"
+	}
+	if systemType == "datetime" || systemType == "datetime2" || systemType == "timestamp" || systemType == "timestamptz" || systemType == "timestamp with time zone" {
+		return "TIMESTAMP"
+	}
+
+	if systemType == "binary" || systemType == "varbinary" || systemType == "image" || systemType == "bytea" {
+		return "BINARY"
+	}
+
+	if systemType == "uniqueidentifier" || systemType == "uuid" {
+		return "UUID"
+	}
+
+	if systemType == "json" {
+		return "JSON"
+	}
+
+	if systemType == "geometry" || systemType == "geography" {
+		return "GEOMETRY"
+	}
+
+	return strings.ToUpper(systemType)
+}
+
+func (ta *MssqlTableAnalyzer) rawColumnToColumnType(rawColumn rawColumnMssql) models.ColumnType {
+	const nullValue int64 = -1
+	stringTypes := map[string]bool{"varchar": true, "char": true, "nvarchar": true, "nchar": true, "text": true, "ntext": true}
+	decimalTypes := map[string]bool{"decimal": true, "numeric": true}
+
+	if stringTypes[rawColumn.systemType] {
+		if rawColumn.systemType == "nvarchar" || rawColumn.systemType == "nchar" {
+			if rawColumn.maxLength > 0 {
+				rawColumn.maxLength = rawColumn.maxLength / 2
+			}
+		}
+
+		rawColumn.precision, rawColumn.scale = nullValue, nullValue
+	} else if decimalTypes[rawColumn.systemType] {
+		rawColumn.maxLength = nullValue
+	} else {
+		rawColumn.maxLength, rawColumn.precision, rawColumn.scale = nullValue, nullValue, nullValue
+	}
+
+	columnType := models.NewColumnType(
+		rawColumn.name,
+		rawColumn.maxLength != nullValue,
+		rawColumn.precision != nullValue || rawColumn.scale != nullValue,
+		rawColumn.userType,
+		rawColumn.systemType,
+		ta.systemTypeToUnifiedType(rawColumn.systemType),
+		rawColumn.nullable,
+		rawColumn.maxLength,
+		rawColumn.precision,
+		rawColumn.scale,
+	)
+
+	return columnType
+}
+
+func (ta *MssqlTableAnalyzer) QueryColumnTypes(
+	ctx context.Context,
+	tableInfo config.TableInfo,
+) ([]models.ColumnType, error) {
+	localCtx, cancel := context.WithTimeout(ctx, 20*time.Second)
+	defer cancel()
+
+	rows, err := ta.db.Query(localCtx, mssqlColumnMetadataQuery, sql.Named("schema", tableInfo.Schema), sql.Named("table", tableInfo.Table))
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var columnTypes []models.ColumnType
+
+	for rows.Next() {
+		var rawColumn rawColumnMssql
+
+		if err := rows.Scan(
+			&rawColumn.name,
+			&rawColumn.userType,
+			&rawColumn.systemType,
+			&rawColumn.nullable,
+			&rawColumn.maxLength,
+			&rawColumn.precision,
+			&rawColumn.scale,
+		); err != nil {
+			return nil, err
+		}
+
+		columnTypes = append(columnTypes, ta.rawColumnToColumnType(rawColumn))
+	}
+
+	return columnTypes, nil
+}
+
+func (ta *MssqlTableAnalyzer) EstimateTotalRows(
+	ctx context.Context,
+	tableInfo config.TableInfo,
+) (int64, error) {
+	query := `
+SELECT SUM(p.rows) AS count
+FROM sys.tables t
+JOIN sys.schemas s ON t.schema_id = s.schema_id
+JOIN sys.partitions p ON t.object_id = p.object_id
+WHERE s.name = @schema AND t.name = @table AND p.index_id IN (0, 1)
+GROUP BY t.name`
+
+	ctxTimeout, cancel := context.WithTimeout(ctx, 1*time.Minute)
+	defer cancel()
+
+	var rowsCount int64
+	err := ta.db.QueryRow(ctxTimeout, query, sql.Named("schema", tableInfo.Schema), sql.Named("table", tableInfo.Table)).Scan(&rowsCount)
+	if err != nil {
+		return 0, err
+	}
+
+	return rowsCount, nil
+}
+
+func (ta *MssqlTableAnalyzer) QueryMaxMinFromColumn(
+	ctx context.Context,
+	tableInfo config.TableInfo,
+	columnName string,
+) (etl.MaxMinColumnResult, error) {
+	query := fmt.Sprintf(`
+SELECT
+	MIN([%s]) AS min_value,
+	MAX([%s]) AS max_value
+FROM [%s].[%s]`, columnName, columnName, tableInfo.Schema, tableInfo.Table)
+
+	ctxTimeout, cancel := context.WithTimeout(ctx, 1*time.Minute)
+	defer cancel()
+
+	result := etl.MaxMinColumnResult{}
+	err := ta.db.QueryRow(ctxTimeout, query).Scan(&result.Min, &result.Max)
+	if err != nil {
+		return etl.MaxMinColumnResult{}, err
+	}
+
+	return result, nil
+}
+
+func (ta *MssqlTableAnalyzer) CalculatePartitionRanges(
+	ctx context.Context,
+	tableInfo config.TableInfo,
+	partitionColumn string,
+	maxPartitions int64,
+	rangeConstraint config.RangeConfig,
+) ([]models.Partition, error) {
+	whereClause := ""
+	args := []any{sql.Named("maxPartitions", maxPartitions)}
+
+	if rangeConstraint.Min != nil || rangeConstraint.Max != nil {
+		var conditions []string
+		if rangeConstraint.Min != nil {
+			minOp := ">"
+			if rangeConstraint.IsMinInclusive {
+				minOp = ">="
+			}
+			conditions = append(conditions, fmt.Sprintf("[%s] %s @rangeMin", partitionColumn, minOp))
+			args = append(args, sql.Named("rangeMin", *rangeConstraint.Min))
+		}
+		if rangeConstraint.Max != nil {
+			maxOp := "<"
+			if rangeConstraint.IsMaxInclusive {
+				maxOp = "<="
+			}
+			conditions = append(conditions, fmt.Sprintf("[%s] %s @rangeMax", partitionColumn, maxOp))
+			args = append(args, sql.Named("rangeMax", *rangeConstraint.Max))
+		}
+		whereClause = "WHERE " + strings.Join(conditions, " AND ")
+	}
+
+	query := fmt.Sprintf(`
+SELECT
+	MIN([%s]) AS lower_limit,
+	MAX([%s]) AS upper_limit
+FROM (SELECT [%s], NTILE(@maxPartitions) OVER (ORDER BY [%s]) AS batch_id FROM [%s].[%s] %s) AS T
+GROUP BY batch_id
+ORDER BY batch_id`,
+		partitionColumn,
+		partitionColumn,
+		partitionColumn,
+		partitionColumn,
+		tableInfo.Schema,
+		tableInfo.Table,
+		whereClause)
+
+	ctxTimeout, cancel := context.WithTimeout(ctx, 1*time.Minute)
+	defer cancel()
+
+	rows, err := ta.db.Query(ctxTimeout, query, args...)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	partitions := make([]models.Partition, 0, maxPartitions)
+
+	for rows.Next() {
+		partition := models.Partition{
+			Id:           uuid.New(),
+			HasRange:     true,
+			RetryCounter: 0,
+			Range: models.PartitionRange{
+				IsMinInclusive: true,
+				IsMaxInclusive: true,
+			},
+		}
+
+		if err := rows.Scan(&partition.Range.Min, &partition.Range.Max); err != nil {
+			return nil, err
+		}
+
+		partitions = append(partitions, partition)
+	}
+
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+
+	return partitions, nil
+}

internal/app/etl/table_analyzers/postgres.go

@@ -0,0 +1,293 @@
+package table_analyzers
+
+import (
+	"context"
+	"fmt"
+	"strings"
+	"time"
+
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
+	dbwrapper "git.ksdemosapps.com/kylesoda/go-migrate/internal/app/db-wrapper"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/etl"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/models"
+	"github.com/google/uuid"
+)
+
+type PostgresTableAnalyzer struct {
+	db dbwrapper.DbWrapper
+}
+
+func NewPostgresTableAnalyzer(db dbwrapper.DbWrapper) etl.TableAnalyzer {
+	return &PostgresTableAnalyzer{db: db}
+}
+
+const postgresColumnMetadataQuery string = `
+SELECT 
+  c.column_name AS name,
+  c.data_type AS user_type,
+  c.udt_name AS system_type,
+  (CASE WHEN c.is_nullable = 'YES' THEN TRUE ELSE FALSE END) AS nullable,
+  COALESCE(c.character_maximum_length, -1) AS max_length,
+  COALESCE(c.numeric_precision, -1) AS precision,
+  COALESCE(c.numeric_scale, -1) AS scale
+FROM information_schema.columns c
+WHERE c.table_schema = $1 AND c.table_name = $2
+ORDER BY c.ordinal_position;`
+
+type rawColumnPostgres struct {
+	name       string
+	userType   string
+	systemType string
+	nullable   bool
+	maxLength  int64
+	precision  int64
+	scale      int64
+}
+
+func (ta *PostgresTableAnalyzer) systemTypeToUnifiedType(systemType string) string {
+	systemType = strings.ToLower(systemType)
+
+	if systemType == "varchar" || systemType == "char" || systemType == "nvarchar" || systemType == "nchar" || systemType == "text" || systemType == "ntext" {
+		return "STRING"
+	}
+
+	if systemType == "int" || systemType == "int4" || systemType == "integer" || systemType == "smallint" || systemType == "int2" || systemType == "bigint" || systemType == "int8" || systemType == "tinyint" {
+		return "INTEGER"
+	}
+
+	if systemType == "decimal" || systemType == "numeric" {
+		return "DECIMAL"
+	}
+
+	if systemType == "float" || systemType == "real" || systemType == "double precision" {
+		return "FLOAT"
+	}
+
+	if systemType == "bit" || systemType == "boolean" {
+		return "BOOLEAN"
+	}
+
+	if systemType == "date" {
+		return "DATE"
+	}
+	if systemType == "time" || systemType == "time without time zone" {
+		return "TIME"
+	}
+	if systemType == "datetime" || systemType == "datetime2" || systemType == "timestamp" || systemType == "timestamptz" || systemType == "timestamp with time zone" {
+		return "TIMESTAMP"
+	}
+
+	if systemType == "binary" || systemType == "varbinary" || systemType == "image" || systemType == "bytea" {
+		return "BINARY"
+	}
+
+	if systemType == "uniqueidentifier" || systemType == "uuid" {
+		return "UUID"
+	}
+
+	if systemType == "json" {
+		return "JSON"
+	}
+
+	if systemType == "geometry" || systemType == "geography" {
+		return "GEOMETRY"
+	}
+
+	return strings.ToUpper(systemType)
+}
+
+func (ta *PostgresTableAnalyzer) rawColumnToColumnType(rawColumn rawColumnPostgres) models.ColumnType {
+	const nullValue int64 = -1
+	stringTypes := map[string]bool{"varchar": true, "char": true, "text": true}
+	decimalTypes := map[string]bool{"decimal": true, "numeric": true}
+
+	if stringTypes[rawColumn.systemType] {
+		rawColumn.precision, rawColumn.scale = nullValue, nullValue
+	} else if decimalTypes[rawColumn.systemType] {
+		rawColumn.maxLength = nullValue
+	} else {
+		rawColumn.maxLength, rawColumn.precision, rawColumn.scale = nullValue, nullValue, nullValue
+	}
+
+	return models.NewColumnType(
+		rawColumn.name,
+		rawColumn.maxLength != nullValue,
+		rawColumn.precision != nullValue || rawColumn.scale != nullValue,
+		rawColumn.userType,
+		rawColumn.systemType,
+		ta.systemTypeToUnifiedType(rawColumn.systemType),
+		rawColumn.nullable,
+		rawColumn.maxLength,
+		rawColumn.precision,
+		rawColumn.scale,
+	)
+}
+
+func (ta *PostgresTableAnalyzer) QueryColumnTypes(
+	ctx context.Context,
+	tableInfo config.TableInfo,
+) ([]models.ColumnType, error) {
+	localCtx, cancel := context.WithTimeout(ctx, 1*time.Minute)
+	defer cancel()
+
+	rows, err := ta.db.Query(localCtx, postgresColumnMetadataQuery, tableInfo.Schema, tableInfo.Table)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var colTypes []models.ColumnType
+
+	for rows.Next() {
+		var column rawColumnPostgres
+
+		if err := rows.Scan(
+			&column.name,
+			&column.userType,
+			&column.systemType,
+			&column.nullable,
+			&column.maxLength,
+			&column.precision,
+			&column.scale,
+		); err != nil {
+			return nil, err
+		}
+
+		colTypes = append(colTypes, ta.rawColumnToColumnType(column))
+	}
+
+	return colTypes, nil
+}
+
+func (ta *PostgresTableAnalyzer) EstimateTotalRows(
+	ctx context.Context,
+	tableInfo config.TableInfo,
+) (int64, error) {
+	query := `
+SELECT reltuples::bigint
+FROM pg_class
+JOIN pg_namespace ON pg_namespace.oid = pg_class.relnamespace
+WHERE pg_namespace.nspname = $1 AND pg_class.relname = $2`
+
+	ctxTimeout, cancel := context.WithTimeout(ctx, 1*time.Minute)
+	defer cancel()
+
+	var estimate int64
+	err := ta.db.QueryRow(ctxTimeout, query, tableInfo.Schema, tableInfo.Table).Scan(&estimate)
+	if err != nil {
+		return 0, err
+	}
+
+	if estimate < 0 {
+		countQuery := fmt.Sprintf(`SELECT COUNT(*) FROM "%s"."%s"`, tableInfo.Schema, tableInfo.Table)
+		err = ta.db.QueryRow(ctxTimeout, countQuery).Scan(&estimate)
+		if err != nil {
+			return 0, err
+		}
+	}
+
+	return estimate, nil
+}
+
+func (ta *PostgresTableAnalyzer) QueryMaxMinFromColumn(
+	ctx context.Context,
+	tableInfo config.TableInfo,
+	columnName string,
+) (etl.MaxMinColumnResult, error) {
+	query := fmt.Sprintf(`SELECT MIN("%s"), MAX("%s") FROM "%s"."%s"`,
+		columnName, columnName, tableInfo.Schema, tableInfo.Table)
+
+	ctxTimeout, cancel := context.WithTimeout(ctx, 1*time.Minute)
+	defer cancel()
+
+	result := etl.MaxMinColumnResult{}
+	err := ta.db.QueryRow(ctxTimeout, query).Scan(&result.Min, &result.Max)
+	if err != nil {
+		return etl.MaxMinColumnResult{}, err
+	}
+
+	return result, nil
+}
+
+func (ta *PostgresTableAnalyzer) CalculatePartitionRanges(
+	ctx context.Context,
+	tableInfo config.TableInfo,
+	partitionColumn string,
+	maxPartitions int64,
+	rangeConstraint config.RangeConfig,
+) ([]models.Partition, error) {
+	whereClause := ""
+	args := []any{maxPartitions}
+
+	if rangeConstraint.Min != nil || rangeConstraint.Max != nil {
+		var conditions []string
+		if rangeConstraint.Min != nil {
+			minOp := ">"
+			if rangeConstraint.IsMinInclusive {
+				minOp = ">="
+			}
+			args = append(args, *rangeConstraint.Min)
+			conditions = append(conditions, fmt.Sprintf(`"%s" %s $%d`, partitionColumn, minOp, len(args)))
+		}
+		if rangeConstraint.Max != nil {
+			maxOp := "<"
+			if rangeConstraint.IsMaxInclusive {
+				maxOp = "<="
+			}
+			args = append(args, *rangeConstraint.Max)
+			conditions = append(conditions, fmt.Sprintf(`"%s" %s $%d`, partitionColumn, maxOp, len(args)))
+		}
+		whereClause = "WHERE " + strings.Join(conditions, " AND ")
+	}
+
+	query := fmt.Sprintf(`
+SELECT MIN("%s") AS lower_limit, MAX("%s") AS upper_limit
+FROM (
+	SELECT "%s", NTILE($1) OVER (ORDER BY "%s") AS batch_id
+	FROM "%s"."%s" %s
+) AS t
+GROUP BY batch_id
+ORDER BY batch_id`,
+		partitionColumn,
+		partitionColumn,
+		partitionColumn,
+		partitionColumn,
+		tableInfo.Schema,
+		tableInfo.Table,
+		whereClause)
+
+	ctxTimeout, cancel := context.WithTimeout(ctx, 1*time.Minute)
+	defer cancel()
+
+	rows, err := ta.db.Query(ctxTimeout, query, args...)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	partitions := make([]models.Partition, 0, maxPartitions)
+
+	for rows.Next() {
+		partition := models.Partition{
+			Id:           uuid.New(),
+			HasRange:     true,
+			RetryCounter: 0,
+			Range: models.PartitionRange{
+				IsMinInclusive: true,
+				IsMaxInclusive: true,
+			},
+		}
+
+		if err := rows.Scan(&partition.Range.Min, &partition.Range.Max); err != nil {
+			return nil, err
+		}
+
+		partitions = append(partitions, partition)
+	}
+
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+
+	return partitions, nil
+}

internal/app/etl/transformers/consume.go

@@ -0,0 +1,119 @@
+package transformers
+
+import (
+	"context"
+	"errors"
+	"sync"
+
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/custom_errors"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/models"
+	"github.com/google/uuid"
+)
+
+type batchAccumulator struct {
+	batchSize int
+	rows      []models.UnknownRowValues
+	parents   []models.BatchRef
+}
+
+func (a *batchAccumulator) add(batch models.Batch) {
+	a.rows = append(a.rows, batch.Rows...)
+	a.parents = append(a.parents, models.BatchRef{Id: batch.Id})
+}
+
+func (a *batchAccumulator) ready() bool {
+	return len(a.rows) >= a.batchSize
+}
+
+func (a *batchAccumulator) flush(ctx context.Context, chOut chan<- models.Batch, wg *sync.WaitGroup) bool {
+	if len(a.rows) == 0 {
+		return true
+	}
+	out := models.Batch{
+		Id:            uuid.New(),
+		ParentBatches: a.parents,
+		Rows:          a.rows,
+	}
+	wg.Add(1)
+	select {
+	case chOut <- out:
+	case <-ctx.Done():
+		wg.Done()
+		return false
+	}
+	a.rows = nil
+	a.parents = nil
+	return true
+}
+
+func sendTransformError(ctx context.Context, err error, ch chan<- custom_errors.JobError) {
+	if errors.Is(err, context.Canceled) || errors.Is(err, context.DeadlineExceeded) {
+		return
+	}
+	var jobErr custom_errors.JobError
+	if je, ok := errors.AsType[*custom_errors.JobError](err); ok {
+		jobErr = *je
+	} else {
+		jobErr = custom_errors.JobError{ShouldCancelJob: true, Msg: "Transformation failed", Prev: err}
+	}
+	select {
+	case ch <- jobErr:
+	case <-ctx.Done():
+	}
+}
+
+func (mssqlTr *MssqlTransformer) Consume(
+	ctx context.Context,
+	columns []models.ColumnType,
+	retryConfig config.RetryConfig,
+	batchSize int,
+	chBatchesIn <-chan models.Batch,
+	chBatchesOut chan<- models.Batch,
+	chJobErrorsOut chan<- custom_errors.JobError,
+	wgActiveBatches *sync.WaitGroup,
+) {
+	transformationPlan := computeTransformationPlan(columns)
+	storagePlan := computeStorageTransformationPlan(ctx, mssqlTr.azureClient, mssqlTr.toStorage, columns, mssqlTr.sourceTable)
+	transformationPlan = append(transformationPlan, storagePlan...)
+
+	acc := &batchAccumulator{batchSize: batchSize}
+
+	for {
+		select {
+		case <-ctx.Done():
+			return
+
+		case batch, ok := <-chBatchesIn:
+			if !ok {
+				acc.flush(ctx, chBatchesOut, wgActiveBatches)
+				return
+			}
+
+			if len(transformationPlan) > 0 {
+				if err := ProcessBatchWithRetries(ctx, &batch, transformationPlan, retryConfig); err != nil {
+					sendTransformError(ctx, err, chJobErrorsOut)
+					return
+				}
+			}
+
+			if batchSize <= 0 {
+				wgActiveBatches.Add(1)
+				select {
+				case chBatchesOut <- batch:
+				case <-ctx.Done():
+					wgActiveBatches.Done()
+					return
+				}
+				continue
+			}
+
+			acc.add(batch)
+			if acc.ready() {
+				if !acc.flush(ctx, chBatchesOut, wgActiveBatches) {
+					return
+				}
+			}
+		}
+	}
+}

internal/app/etl/transformers/consume_test.go

@@ -0,0 +1,545 @@
+package transformers
+
+import (
+	"context"
+	"errors"
+	"sync"
+	"testing"
+	"time"
+
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/custom_errors"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/models"
+	"github.com/google/uuid"
+)
+
+const testTimeout = 2 * time.Second
+
+func makeBatch(numRows int) models.Batch {
+	rows := make([]models.UnknownRowValues, numRows)
+	for i := range rows {
+		rows[i] = models.UnknownRowValues{i}
+	}
+	return models.Batch{Id: uuid.New(), Rows: rows}
+}
+
+func noRetry() config.RetryConfig {
+	return config.RetryConfig{Attempts: 1}
+}
+
+func newTransformer() *MssqlTransformer {
+	return &MssqlTransformer{}
+}
+
+func uuidColumn() models.ColumnType {
+	return models.NewColumnType("col_uuid", false, false, "uniqueidentifier", "uniqueidentifier", "string", false, 0, 0, 0)
+}
+
+func runConsume(
+	ctx context.Context,
+	tr *MssqlTransformer,
+	columns []models.ColumnType,
+	batchSize int,
+	chIn <-chan models.Batch,
+	chOut chan<- models.Batch,
+	chErr chan<- custom_errors.JobError,
+	wg *sync.WaitGroup,
+) <-chan struct{} {
+	done := make(chan struct{})
+	go func() {
+		tr.Consume(ctx, columns, noRetry(), batchSize, chIn, chOut, chErr, wg)
+		close(done)
+	}()
+	return done
+}
+
+func drainOut(chOut <-chan models.Batch, wg *sync.WaitGroup) []models.Batch {
+	var batches []models.Batch
+	for {
+		select {
+		case b := <-chOut:
+			batches = append(batches, b)
+			wg.Done()
+		default:
+			return batches
+		}
+	}
+}
+func TestBatchAccumulator_Add(t *testing.T) {
+	acc := &batchAccumulator{batchSize: 5}
+	b1 := makeBatch(2)
+	b2 := makeBatch(3)
+
+	acc.add(b1)
+	acc.add(b2)
+
+	if len(acc.rows) != 5 {
+		t.Errorf("expected 5 rows, got %d", len(acc.rows))
+	}
+	if len(acc.parents) != 2 {
+		t.Fatalf("expected 2 parents, got %d", len(acc.parents))
+	}
+	if acc.parents[0].Id != b1.Id || acc.parents[1].Id != b2.Id {
+		t.Error("parent IDs do not match source batch IDs")
+	}
+}
+
+func TestBatchAccumulator_Ready(t *testing.T) {
+	acc := &batchAccumulator{batchSize: 3}
+	acc.add(makeBatch(2))
+	if acc.ready() {
+		t.Error("should not be ready with 2 rows and batchSize=3")
+	}
+	acc.add(makeBatch(1))
+	if !acc.ready() {
+		t.Error("should be ready with 3 rows and batchSize=3")
+	}
+}
+
+func TestBatchAccumulator_Flush_Empty(t *testing.T) {
+	acc := &batchAccumulator{batchSize: 5}
+	chOut := make(chan models.Batch, 1)
+	var wg sync.WaitGroup
+
+	if !acc.flush(context.Background(), chOut, &wg) {
+		t.Error("flush on empty accumulator should return true")
+	}
+	if len(chOut) != 0 {
+		t.Error("flush on empty accumulator should send nothing")
+	}
+}
+
+func TestBatchAccumulator_Flush_Success(t *testing.T) {
+	acc := &batchAccumulator{batchSize: 2}
+	b := makeBatch(2)
+	acc.add(b)
+
+	chOut := make(chan models.Batch, 1)
+	var wg sync.WaitGroup
+
+	if !acc.flush(context.Background(), chOut, &wg) {
+		t.Fatal("flush should return true on success")
+	}
+
+	select {
+	case out := <-chOut:
+		wg.Done()
+		if len(out.Rows) != 2 {
+			t.Errorf("expected 2 rows in flushed batch, got %d", len(out.Rows))
+		}
+		if len(out.ParentBatches) != 1 || out.ParentBatches[0].Id != b.Id {
+			t.Error("flushed batch should reference the source batch as parent")
+		}
+	default:
+		t.Error("expected a batch in chOut after flush")
+	}
+
+	if len(acc.rows) != 0 || len(acc.parents) != 0 {
+		t.Error("accumulator state should be reset after flush")
+	}
+	wg.Wait()
+}
+
+func TestBatchAccumulator_Flush_ContextCancelled(t *testing.T) {
+	acc := &batchAccumulator{batchSize: 2}
+	acc.add(makeBatch(2))
+
+	chOut := make(chan models.Batch)
+	var wg sync.WaitGroup
+
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel()
+
+	if acc.flush(ctx, chOut, &wg) {
+		t.Error("flush should return false when context is cancelled")
+	}
+
+	wg.Wait()
+}
+
+func TestSendTransformError_PlainError(t *testing.T) {
+	ch := make(chan custom_errors.JobError, 1)
+
+	sendTransformError(context.Background(), errors.New("something broke"), ch)
+
+	select {
+	case e := <-ch:
+		if !e.ShouldCancelJob {
+			t.Error("plain error should produce ShouldCancelJob=true")
+		}
+	default:
+		t.Error("expected a job error in the channel")
+	}
+}
+
+func TestSendTransformError_JobError_Passthrough(t *testing.T) {
+	ch := make(chan custom_errors.JobError, 1)
+	original := &custom_errors.JobError{ShouldCancelJob: false, Msg: "custom msg"}
+
+	sendTransformError(context.Background(), original, ch)
+
+	select {
+	case e := <-ch:
+		if e.ShouldCancelJob != false || e.Msg != "custom msg" {
+			t.Errorf("JobError should pass through unchanged, got %+v", e)
+		}
+	default:
+		t.Error("expected a job error in the channel")
+	}
+}
+
+func TestSendTransformError_ContextCancelled_Silent(t *testing.T) {
+	ch := make(chan custom_errors.JobError, 1)
+
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel()
+
+	sendTransformError(ctx, context.Canceled, ch)
+
+	if len(ch) != 0 {
+		t.Error("context.Canceled should be silently dropped")
+	}
+}
+
+func TestSendTransformError_DeadlineExceeded_Silent(t *testing.T) {
+	ch := make(chan custom_errors.JobError, 1)
+
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel()
+
+	sendTransformError(ctx, context.DeadlineExceeded, ch)
+
+	if len(ch) != 0 {
+		t.Error("context.DeadlineExceeded should be silently dropped")
+	}
+}
+
+func TestConsume_Passthrough_PreservesOriginalBatch(t *testing.T) {
+	tr := newTransformer()
+	chIn := make(chan models.Batch, 1)
+	chOut := make(chan models.Batch, 1)
+	chErr := make(chan custom_errors.JobError, 1)
+	var wg sync.WaitGroup
+
+	batch := makeBatch(3)
+	chIn <- batch
+	close(chIn)
+
+	done := runConsume(context.Background(), tr, nil, 0, chIn, chOut, chErr, &wg)
+
+	select {
+	case got := <-chOut:
+		wg.Done()
+		if got.Id != batch.Id {
+			t.Error("passthrough should preserve the original batch ID")
+		}
+		if len(got.Rows) != 3 {
+			t.Errorf("expected 3 rows, got %d", len(got.Rows))
+		}
+	case <-time.After(testTimeout):
+		t.Fatal("timeout waiting for output batch")
+	}
+
+	<-done
+	wg.Wait()
+}
+
+func TestConsume_Passthrough_WaitGroupBalanced(t *testing.T) {
+	tr := newTransformer()
+	chIn := make(chan models.Batch, 3)
+	chOut := make(chan models.Batch, 3)
+	chErr := make(chan custom_errors.JobError, 1)
+	var wg sync.WaitGroup
+
+	for range 3 {
+		chIn <- makeBatch(1)
+	}
+	close(chIn)
+
+	done := runConsume(context.Background(), tr, nil, 0, chIn, chOut, chErr, &wg)
+	<-done
+
+	batches := drainOut(chOut, &wg)
+	if len(batches) != 3 {
+		t.Errorf("expected 3 output batches, got %d", len(batches))
+	}
+
+	wg.Wait()
+}
+
+func TestConsume_Accumulation_FlushOnThreshold(t *testing.T) {
+	tr := newTransformer()
+	chIn := make(chan models.Batch, 3)
+	chOut := make(chan models.Batch, 2)
+	chErr := make(chan custom_errors.JobError, 1)
+	var wg sync.WaitGroup
+
+	for range 3 {
+		chIn <- makeBatch(1)
+	}
+	close(chIn)
+
+	done := runConsume(context.Background(), tr, nil, 3, chIn, chOut, chErr, &wg)
+	<-done
+
+	batches := drainOut(chOut, &wg)
+	if len(batches) != 1 {
+		t.Fatalf("expected 1 accumulated batch, got %d", len(batches))
+	}
+	if len(batches[0].Rows) != 3 {
+		t.Errorf("expected 3 rows in accumulated batch, got %d", len(batches[0].Rows))
+	}
+	wg.Wait()
+}
+
+func TestConsume_Accumulation_FlushOnClose(t *testing.T) {
+	tr := newTransformer()
+	chIn := make(chan models.Batch, 2)
+	chOut := make(chan models.Batch, 2)
+	chErr := make(chan custom_errors.JobError, 1)
+	var wg sync.WaitGroup
+
+	chIn <- makeBatch(1)
+	chIn <- makeBatch(1)
+	close(chIn)
+
+	done := runConsume(context.Background(), tr, nil, 10, chIn, chOut, chErr, &wg)
+	<-done
+
+	batches := drainOut(chOut, &wg)
+	if len(batches) != 1 {
+		t.Fatalf("expected 1 batch flushed on close, got %d", len(batches))
+	}
+	if len(batches[0].Rows) != 2 {
+		t.Errorf("expected 2 rows, got %d", len(batches[0].Rows))
+	}
+	wg.Wait()
+}
+
+func TestConsume_Accumulation_TracksAllParentBatches(t *testing.T) {
+	tr := newTransformer()
+	chIn := make(chan models.Batch, 2)
+	chOut := make(chan models.Batch, 2)
+	chErr := make(chan custom_errors.JobError, 1)
+	var wg sync.WaitGroup
+
+	b1 := makeBatch(1)
+	b2 := makeBatch(1)
+	chIn <- b1
+	chIn <- b2
+	close(chIn)
+
+	done := runConsume(context.Background(), tr, nil, 10, chIn, chOut, chErr, &wg)
+	<-done
+
+	batches := drainOut(chOut, &wg)
+	if len(batches) != 1 {
+		t.Fatalf("expected 1 output batch, got %d", len(batches))
+	}
+	parents := batches[0].ParentBatches
+	if len(parents) != 2 {
+		t.Fatalf("expected 2 parent refs, got %d", len(parents))
+	}
+	if parents[0].Id != b1.Id || parents[1].Id != b2.Id {
+		t.Error("parent IDs should match source batch IDs in order")
+	}
+	wg.Wait()
+}
+
+func TestConsume_Accumulation_MultipleFlushes(t *testing.T) {
+	tr := newTransformer()
+	chIn := make(chan models.Batch, 5)
+	chOut := make(chan models.Batch, 5)
+	chErr := make(chan custom_errors.JobError, 1)
+	var wg sync.WaitGroup
+
+	for range 5 {
+		chIn <- makeBatch(1)
+	}
+	close(chIn)
+
+	done := runConsume(context.Background(), tr, nil, 2, chIn, chOut, chErr, &wg)
+	<-done
+
+	batches := drainOut(chOut, &wg)
+	if len(batches) != 3 {
+		t.Fatalf("expected 3 output batches (2+2+1 rows), got %d", len(batches))
+	}
+	totalRows := 0
+	for _, b := range batches {
+		totalRows += len(b.Rows)
+	}
+	if totalRows != 5 {
+		t.Errorf("expected 5 total rows across all batches, got %d", totalRows)
+	}
+	wg.Wait()
+}
+
+func TestConsume_EmptyInput_NoOutput(t *testing.T) {
+	tr := newTransformer()
+	chIn := make(chan models.Batch)
+	chOut := make(chan models.Batch, 1)
+	chErr := make(chan custom_errors.JobError, 1)
+	var wg sync.WaitGroup
+
+	close(chIn)
+
+	done := runConsume(context.Background(), tr, nil, 5, chIn, chOut, chErr, &wg)
+
+	select {
+	case <-done:
+	case <-time.After(testTimeout):
+		t.Fatal("timeout: Consume did not exit after empty input channel was closed")
+	}
+
+	if len(chOut) != 0 {
+		t.Error("expected no output for empty input")
+	}
+	wg.Wait()
+}
+
+func TestConsume_TransformError_SendsJobError(t *testing.T) {
+	tr := newTransformer()
+	col := uuidColumn()
+
+	chIn := make(chan models.Batch, 1)
+	chOut := make(chan models.Batch, 1)
+	chErr := make(chan custom_errors.JobError, 1)
+	var wg sync.WaitGroup
+
+	batch := models.Batch{
+		Id:   uuid.New(),
+		Rows: []models.UnknownRowValues{{[]byte{1, 2, 3}}},
+	}
+	chIn <- batch
+
+	done := runConsume(context.Background(), tr, []models.ColumnType{col}, 0, chIn, chOut, chErr, &wg)
+
+	select {
+	case err := <-chErr:
+		if !err.ShouldCancelJob {
+			t.Error("transform error should set ShouldCancelJob=true")
+		}
+	case <-time.After(testTimeout):
+		t.Fatal("timeout: expected a job error from transform failure")
+	}
+
+	<-done
+	wg.Wait()
+}
+
+func TestConsume_TransformError_NoOutputForwarded(t *testing.T) {
+	tr := newTransformer()
+	col := uuidColumn()
+
+	chIn := make(chan models.Batch, 1)
+	chOut := make(chan models.Batch, 1)
+	chErr := make(chan custom_errors.JobError, 1)
+	var wg sync.WaitGroup
+
+	batch := models.Batch{
+		Id:   uuid.New(),
+		Rows: []models.UnknownRowValues{{[]byte{1, 2, 3}}},
+	}
+	chIn <- batch
+
+	done := runConsume(context.Background(), tr, []models.ColumnType{col}, 0, chIn, chOut, chErr, &wg)
+	<-done
+
+	if len(chOut) != 0 {
+		t.Error("no batch should be forwarded when transformation fails")
+	}
+	wg.Wait()
+}
+
+func TestConsume_ContextCancellation_Exits(t *testing.T) {
+	tr := newTransformer()
+	chIn := make(chan models.Batch)
+	chOut := make(chan models.Batch, 1)
+	chErr := make(chan custom_errors.JobError, 1)
+	var wg sync.WaitGroup
+
+	ctx, cancel := context.WithCancel(context.Background())
+	done := runConsume(ctx, tr, nil, 0, chIn, chOut, chErr, &wg)
+
+	cancel()
+
+	select {
+	case <-done:
+	case <-time.After(testTimeout):
+		t.Fatal("timeout: Consume did not exit after context cancellation")
+	}
+	wg.Wait()
+}
+
+func TestConsume_Transform_DatetimeConvertedToUTC(t *testing.T) {
+	tr := newTransformer()
+	col := models.NewColumnType("col_dt", false, false, "datetime", "datetime", "timestamp", false, 0, 0, 0)
+
+	chIn := make(chan models.Batch, 1)
+	chOut := make(chan models.Batch, 1)
+	chErr := make(chan custom_errors.JobError, 1)
+	var wg sync.WaitGroup
+
+	nonUTC := time.Date(2024, 1, 15, 12, 0, 0, 0, time.FixedZone("EST", -5*3600))
+	batch := models.Batch{
+		Id:   uuid.New(),
+		Rows: []models.UnknownRowValues{{nonUTC}},
+	}
+	chIn <- batch
+	close(chIn)
+
+	done := runConsume(context.Background(), tr, []models.ColumnType{col}, 0, chIn, chOut, chErr, &wg)
+	<-done
+
+	select {
+	case got := <-chOut:
+		wg.Done()
+		result, ok := got.Rows[0][0].(time.Time)
+		if !ok {
+			t.Fatal("expected time.Time in output row")
+		}
+		if result.Location() != time.UTC {
+			t.Errorf("expected UTC location after transform, got %v", result.Location())
+		}
+	default:
+		t.Error("expected an output batch")
+	}
+
+	wg.Wait()
+}
+
+func TestConsume_Transform_NilValueSkipped(t *testing.T) {
+	tr := newTransformer()
+	col := uuidColumn()
+
+	chIn := make(chan models.Batch, 1)
+	chOut := make(chan models.Batch, 1)
+	chErr := make(chan custom_errors.JobError, 1)
+	var wg sync.WaitGroup
+
+	batch := models.Batch{
+		Id:   uuid.New(),
+		Rows: []models.UnknownRowValues{{nil}},
+	}
+	chIn <- batch
+	close(chIn)
+
+	done := runConsume(context.Background(), tr, []models.ColumnType{col}, 0, chIn, chOut, chErr, &wg)
+	<-done
+
+	select {
+	case got := <-chOut:
+		wg.Done()
+		if got.Rows[0][0] != nil {
+			t.Error("nil value should pass through unchanged")
+		}
+	default:
+		t.Error("expected an output batch even when value is nil")
+	}
+
+	if len(chErr) != 0 {
+		t.Error("nil value should not produce an error")
+	}
+	wg.Wait()
+}

internal/app/etl/transformers/mssql.go

@@ -0,0 +1,21 @@
+package transformers
+
+import (
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/azure"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/etl"
+)
+
+type MssqlTransformer struct {
+	toStorage   config.ToStorageConfig
+	sourceTable config.SourceTableInfo
+	azureClient *azure.Client
+}
+
+func NewMssqlTransformer(toStorage config.ToStorageConfig, sourceTable config.SourceTableInfo, azureClient *azure.Client) etl.Transformer {
+	return &MssqlTransformer{
+		toStorage:   toStorage,
+		sourceTable: sourceTable,
+		azureClient: azureClient,
+	}
+}

internal/app/etl/transformers/plan.go

@@ -0,0 +1,181 @@
+package transformers
+
+import (
+	"context"
+	"fmt"
+	"path"
+	"strings"
+	"time"
+
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/azure"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/custom_errors"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/etl"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/models"
+	"github.com/google/uuid"
+	"github.com/sirupsen/logrus"
+)
+
+func computeTransformationPlan(columns []models.ColumnType) []etl.ColumnTransformPlan {
+	var plan []etl.ColumnTransformPlan
+
+	for i, col := range columns {
+		switch col.SystemType() {
+		case "uniqueidentifier":
+			plan = append(plan, etl.ColumnTransformPlan{
+				Index: i,
+				Fn: func(v any) (any, error) {
+					if b, ok := v.([]byte); ok && b != nil {
+						return mssqlUuidToBigEndian(b)
+					}
+					return v, nil
+				},
+			})
+
+		case "geometry", "geography":
+			plan = append(plan, etl.ColumnTransformPlan{
+				Index: i,
+				Fn: func(v any) (any, error) {
+					if b, ok := v.([]byte); ok && b != nil {
+						return wkbToEwkbWithSrid(b, 4326)
+					}
+					return v, nil
+				},
+			})
+
+		case "datetime", "datetime2":
+			plan = append(plan, etl.ColumnTransformPlan{
+				Index: i,
+				Fn: func(v any) (any, error) {
+					if t, ok := v.(time.Time); ok {
+						return ensureUTC(t), nil
+					}
+					return v, nil
+				},
+			})
+		}
+	}
+
+	return plan
+}
+
+func computePostgresTransformationPlan(columns []models.ColumnType) []etl.ColumnTransformPlan {
+	var plan []etl.ColumnTransformPlan
+
+	for i, col := range columns {
+		switch col.SystemType() {
+		case "int2", "int4", "int8", "integer", "smallint", "bigint":
+			plan = append(plan, etl.ColumnTransformPlan{
+				Index: i,
+				Fn: func(v any) (any, error) {
+					if v64, ok := ToInt64(v); ok {
+						return v64, nil
+					}
+					return v, nil
+				},
+			})
+
+		case "uuid":
+			plan = append(plan, etl.ColumnTransformPlan{
+				Index: i,
+				Fn: func(v any) (any, error) {
+					switch b := v.(type) {
+					case []byte:
+						if b != nil {
+							return bigEndianToMssqlUuid(b)
+						}
+					case [16]byte:
+						return bigEndianToMssqlUuid(b[:])
+					}
+					return v, nil
+				},
+			})
+
+		case "geometry":
+			plan = append(plan, etl.ColumnTransformPlan{
+				Index: i,
+				Fn: func(v any) (any, error) {
+					if b, ok := v.([]byte); ok && b != nil {
+						return ewkbToMssqlGeo(b, false)
+					}
+					return v, nil
+				},
+			})
+
+		case "geography":
+			plan = append(plan, etl.ColumnTransformPlan{
+				Index: i,
+				Fn: func(v any) (any, error) {
+					if b, ok := v.([]byte); ok && b != nil {
+						return ewkbToMssqlGeo(b, true)
+					}
+					return v, nil
+				},
+			})
+		}
+	}
+
+	return plan
+}
+
+func computeStorageTransformationPlan(
+	ctx context.Context,
+	azureClient *azure.Client,
+	toStorage config.ToStorageConfig,
+	sourceColumns []models.ColumnType,
+	sourceTable config.SourceTableInfo,
+) []etl.ColumnTransformPlan {
+	if azureClient == nil || len(toStorage.Columns) == 0 {
+		return nil
+	}
+
+	colIndex := make(map[string]int, len(sourceColumns))
+	for i, col := range sourceColumns {
+		colIndex[strings.ToUpper(col.Name())] = i
+	}
+
+	var plan []etl.ColumnTransformPlan
+	for _, storageCol := range toStorage.Columns {
+		if storageCol.Mode != "REFERENCE_ONLY" {
+			logrus.Warnf("to_storage: unsupported mode %q for column %s — skipping", storageCol.Mode, storageCol.Source)
+			continue
+		}
+
+		idx, ok := colIndex[strings.ToUpper(storageCol.Source)]
+		if !ok {
+			logrus.Warnf("to_storage: source column %q not found in source schema — skipping", storageCol.Source)
+			continue
+		}
+
+		sourceColName := storageCol.Source
+		schema := sourceTable.Schema
+		table := sourceTable.Table
+
+		plan = append(plan, etl.ColumnTransformPlan{
+			Index: idx,
+			Fn: func(v any) (any, error) {
+				if v == nil {
+					return nil, nil
+				}
+				b, ok := v.([]byte)
+				if !ok {
+					logrus.Warnf("to_storage: expected []byte for %s.%s.%s, got %T — passing through", schema, table, sourceColName, v)
+					return v, nil
+				}
+				// start := time.Now()
+				blobPath := path.Join(storageCol.Prefix, uuid.New().String())
+				blobURL, err := azureClient.UploadAndGetURL(ctx, blobPath, b)
+				if err != nil {
+					return nil, &custom_errors.JobError{
+						Msg:  fmt.Sprintf("Error uploading %s.%s.%s", schema, table, sourceColName),
+						Prev: err,
+					}
+				}
+
+				// logrus.Debugf(`Succesfully uploaded "%s", (%vms)`, blobURL, time.Since(start).Milliseconds())
+				return blobURL, nil
+			},
+		})
+	}
+	return plan
+}

internal/app/etl/transformers/postgres.go

@@ -0,0 +1,72 @@
+package transformers
+
+import (
+	"context"
+	"sync"
+
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/custom_errors"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/etl"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/models"
+)
+
+type PostgresTransformer struct {
+	sourceTable config.SourceTableInfo
+}
+
+func NewPostgresTransformer(sourceTable config.SourceTableInfo) etl.Transformer {
+	return &PostgresTransformer{sourceTable: sourceTable}
+}
+
+func (pgTr *PostgresTransformer) Consume(
+	ctx context.Context,
+	columns []models.ColumnType,
+	retryConfig config.RetryConfig,
+	batchSize int,
+	chBatchesIn <-chan models.Batch,
+	chBatchesOut chan<- models.Batch,
+	chJobErrorsOut chan<- custom_errors.JobError,
+	wgActiveBatches *sync.WaitGroup,
+) {
+	transformationPlan := computePostgresTransformationPlan(columns)
+
+	acc := &batchAccumulator{batchSize: batchSize}
+
+	for {
+		select {
+		case <-ctx.Done():
+			return
+
+		case batch, ok := <-chBatchesIn:
+			if !ok {
+				acc.flush(ctx, chBatchesOut, wgActiveBatches)
+				return
+			}
+
+			if len(transformationPlan) > 0 {
+				if err := ProcessBatchWithRetries(ctx, &batch, transformationPlan, retryConfig); err != nil {
+					sendTransformError(ctx, err, chJobErrorsOut)
+					return
+				}
+			}
+
+			if batchSize <= 0 {
+				wgActiveBatches.Add(1)
+				select {
+				case chBatchesOut <- batch:
+				case <-ctx.Done():
+					wgActiveBatches.Done()
+					return
+				}
+				continue
+			}
+
+			acc.add(batch)
+			if acc.ready() {
+				if !acc.flush(ctx, chBatchesOut, wgActiveBatches) {
+					return
+				}
+			}
+		}
+	}
+}

internal/app/etl/transformers/process-with-retries.go

@@ -0,0 +1,73 @@
+package transformers
+
+import (
+	"context"
+	"errors"
+	"time"
+
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/custom_errors"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/etl"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/models"
+)
+
+const processBatchCtxCheck = 4096
+
+func ProcessBatchWithRetries(
+	ctx context.Context,
+	batch *models.Batch,
+	transformationPlan []etl.ColumnTransformPlan,
+	retryConfig config.RetryConfig,
+) error {
+	for i, rowValues := range batch.Rows {
+		if i%processBatchCtxCheck == 0 {
+			if err := ctx.Err(); err != nil {
+				return err
+			}
+		}
+
+		for _, task := range transformationPlan {
+			val := rowValues[task.Index]
+			if val == nil {
+				continue
+			}
+
+			var lastErr error
+			success := false
+
+			for attempt := 0; attempt < retryConfig.Attempts; attempt++ {
+				transformed, err := task.Fn(val)
+				if err == nil {
+					rowValues[task.Index] = transformed
+					success = true
+					break
+				}
+
+				lastErr = err
+				if jobError, ok := errors.AsType[*custom_errors.JobError](err); ok {
+					if jobError.ShouldCancelJob {
+						return jobError
+					}
+				}
+
+				if attempt == retryConfig.Attempts-1 {
+					break
+				}
+
+				delay := custom_errors.ComputeBackoffDelay(
+					attempt,
+					retryConfig.BaseDelayMs,
+					retryConfig.MaxDelayMs,
+					retryConfig.MaxJitterMs,
+				)
+				time.Sleep(delay)
+			}
+
+			if !success {
+				return lastErr
+			}
+		}
+	}
+
+	return nil
+}

internal/app/etl/transformers/utils.go

@@ -0,0 +1,105 @@
+package transformers
+
+import (
+	"encoding/binary"
+	"errors"
+	"time"
+
+	mssqlclrgeo "github.com/gaspardle/go-mssqlclrgeo"
+)
+
+func mssqlUuidToBigEndian(mssqlUuid []byte) ([]byte, error) {
+	if len(mssqlUuid) != 16 {
+		return nil, errors.New("Invalid uuid")
+	}
+
+	pgUuid := make([]byte, 16)
+	pgUuid[0], pgUuid[1], pgUuid[2], pgUuid[3] = mssqlUuid[3], mssqlUuid[2], mssqlUuid[1], mssqlUuid[0]
+	pgUuid[4], pgUuid[5] = mssqlUuid[5], mssqlUuid[4]
+	pgUuid[6], pgUuid[7] = mssqlUuid[7], mssqlUuid[6]
+	copy(pgUuid[8:], mssqlUuid[8:])
+
+	return pgUuid, nil
+}
+
+const sridFlag = 0x20000000
+
+func wkbToEwkbWithSrid(geometry []byte, srid int) ([]byte, error) {
+	if len(geometry) < 5 {
+		return nil, errors.New("Invalid wkb")
+	}
+
+	var byteOrder binary.ByteOrder
+	if geometry[0] == 0 {
+		byteOrder = binary.BigEndian
+	} else {
+		byteOrder = binary.LittleEndian
+	}
+
+	wkbType := byteOrder.Uint32(geometry[1:5])
+	if wkbType&sridFlag != 0 {
+		return geometry, nil
+	}
+
+	ewkbType := wkbType | sridFlag
+
+	result := make([]byte, len(geometry)+4)
+
+	result[0] = geometry[0]
+
+	byteOrder.PutUint32(result[1:5], ewkbType)
+
+	byteOrder.PutUint32(result[5:9], uint32(srid))
+
+	copy(result[9:], geometry[5:])
+
+	return result, nil
+}
+
+func ensureUTC(t time.Time) time.Time {
+	if t.Location() == time.UTC {
+		return t
+	}
+
+	return time.Date(t.Year(), t.Month(), t.Day(), t.Hour(), t.Minute(), t.Second(), t.Nanosecond(), time.UTC)
+}
+
+func bigEndianToMssqlUuid(pgUuid []byte) ([]byte, error) {
+	if len(pgUuid) != 16 {
+		return nil, errors.New("Invalid uuid")
+	}
+
+	mssqlUuid := make([]byte, 16)
+	mssqlUuid[0], mssqlUuid[1], mssqlUuid[2], mssqlUuid[3] = pgUuid[3], pgUuid[2], pgUuid[1], pgUuid[0]
+	mssqlUuid[4], mssqlUuid[5] = pgUuid[5], pgUuid[4]
+	mssqlUuid[6], mssqlUuid[7] = pgUuid[7], pgUuid[6]
+	copy(mssqlUuid[8:], pgUuid[8:])
+
+	return mssqlUuid, nil
+}
+
+func ewkbToMssqlGeo(ewkb []byte, isGeography bool) ([]byte, error) {
+	if len(ewkb) < 5 {
+		return nil, errors.New("Invalid ewkb")
+	}
+	// mssqlclrgeo reads the SRID flag and bytes directly from EWKB,
+	// so no pre-processing needed — pass through as-is.
+	return mssqlclrgeo.WkbToUdtGeo(ewkb, isGeography)
+}
+
+func ToInt64(v any) (int64, bool) {
+	switch t := v.(type) {
+	case int:
+		return int64(t), true
+	case int8:
+		return int64(t), true
+	case int16:
+		return int64(t), true
+	case int32:
+		return int64(t), true
+	case int64:
+		return int64(t), true
+	default:
+		return 0, false
+	}
+}

internal/app/etl/types.go

@@ -0,0 +1,61 @@
+package etl
+
+import (
+	"context"
+	"sync"
+
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/custom_errors"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/models"
+)
+
+type TransformerFunc func(any) (any, error)
+
+type ColumnTransformPlan struct {
+	Index int
+	Fn    TransformerFunc
+}
+
+type Transformer interface {
+	Consume(
+		ctx context.Context,
+		columns []models.ColumnType,
+		retryConfig config.RetryConfig,
+		batchSize int,
+		chBatchesIn <-chan models.Batch,
+		chBatchesOut chan<- models.Batch,
+		chJobErrorsOut chan<- custom_errors.JobError,
+		wgActiveBatches *sync.WaitGroup,
+	)
+}
+
+type MaxMinColumnResult struct {
+	Max int64
+	Min int64
+}
+
+type TableAnalyzer interface {
+	QueryColumnTypes(
+		ctx context.Context,
+		tableInfo config.TableInfo,
+	) ([]models.ColumnType, error)
+
+	EstimateTotalRows(
+		ctx context.Context,
+		tableInfo config.TableInfo,
+	) (int64, error)
+
+	QueryMaxMinFromColumn(
+		ctx context.Context,
+		tableInfo config.TableInfo,
+		columnName string,
+	) (MaxMinColumnResult, error)
+
+	CalculatePartitionRanges(
+		ctx context.Context,
+		tableInfo config.TableInfo,
+		partitionColumn string,
+		maxPartitions int64,
+		rangeConstraint config.RangeConfig,
+	) ([]models.Partition, error)
+}

internal/app/models/colum-type.go

@@ -1,4 +1,4 @@
-package main
+package models
 
 type ColumnType struct {
 	name string
@@ -42,3 +42,29 @@ func (c *ColumnType) Nullable() bool {
 func (c *ColumnType) Type() string {
 	return c.unifiedType
 }
+
+func NewColumnType(
+	name string,
+	hasMaxLength bool,
+	hasPrecisionScale bool,
+	userType string,
+	systemType string,
+	unifiedType string,
+	nullable bool,
+	maxLength int64,
+	precision int64,
+	scale int64,
+) ColumnType {
+	return ColumnType{
+		name,
+		hasMaxLength,
+		hasPrecisionScale,
+		userType,
+		systemType,
+		unifiedType,
+		nullable,
+		maxLength,
+		precision,
+		scale,
+	}
+}

internal/app/models/main.go

@@ -0,0 +1,46 @@
+package models
+
+import (
+	"time"
+
+	"github.com/google/uuid"
+)
+
+type UnknownRowValues = []any
+
+type BatchRef struct {
+	Id          uuid.UUID
+	PartitionId uuid.UUID
+}
+
+type Batch struct {
+	Id            uuid.UUID
+	ParentBatches []BatchRef
+	Rows          []UnknownRowValues
+	RetryCounter  int
+}
+
+type PartitionRange struct {
+	Min            int64
+	Max            int64
+	IsMinInclusive bool
+	IsMaxInclusive bool
+}
+
+type Partition struct {
+	Id           uuid.UUID
+	ParentId     uuid.UUID
+	Range        PartitionRange
+	HasRange     bool
+	RetryCounter int
+}
+
+type JobResult struct {
+	JobName    string
+	StartTime  time.Time
+	Duration   time.Duration
+	RowsRead   int64
+	RowsLoaded int64
+	RowsFailed int64
+	Error      error
+}

openspec/changes/bidirectional-transforms/plan.md

@@ -0,0 +1,137 @@
+# Plan: Bidirectional Transformation Support
+
+## Goal
+
+Make the transformation pipeline direction-aware. Currently hardcoded to MSSQL → PG; add support for PG → MSSQL by applying inverse transformations when `SourceDbType == "postgres"`.
+
+Excluded: `to_storage` Azure blob upload (not reversible).
+
+---
+
+## Hardcoded wiring to fix
+
+| File | Line | Change |
+|---|---|---|
+| `cmd/go_migrate/process.go` | 51 | Branch on `SourceDbType`: `"sqlserver"` → `NewMssqlTransformer`, `"postgres"` → `NewPostgresTransformer` |
+| `cmd/go_migrate/main.go` | 166–167 | Branch on source/target type for both `TableAnalyzer` selections |
+
+---
+
+## Transformations
+
+### Forward (MSSQL → PG) — unchanged
+
+| Column type | Function | File |
+|---|---|---|
+| `uniqueidentifier` | `mssqlUuidToBigEndian` | `utils.go:9` |
+| `geometry`/`geography` | `wkbToEwkbWithSrid` | `utils.go:25` |
+| `datetime`/`datetime2` | `ensureUTC` | `utils.go:57` |
+
+### Inverse (PG → MSSQL) — new
+
+| PG system type | Action |
+|---|---|
+| `uuid` | `bigEndianToMssqlUuid`: re-swap bytes [0-3], [4-5], [6-7] |
+| `geometry` | `ewkbToMssqlGeo(v, false)`: strip SRID → WKB → `WkbToUdtGeo` |
+| `geography` | `ewkbToMssqlGeo(v, true)`: strip SRID → WKB → `WkbToUdtGeo` |
+| `timestamp`/`timestamptz` | no-op |
+
+**Geometry note**: MSSQL rejects plain WKB via bulk protocol. Must use `mssqlclrgeo.WkbToUdtGeo(wkb, isGeography)` (already in go.mod). PG extractor already emits EWKB via `ST_AsEWKB()`.
+
+---
+
+## New utility functions (`transformers/utils.go`)
+
+### `bigEndianToMssqlUuid(v []byte) []byte`
+```
+out[0..3]  = v[3,2,1,0]
+out[4..5]  = v[5,4]
+out[6..7]  = v[7,6]
+out[8..15] = v[8..15]
+```
+
+### `ewkbToMssqlGeo(ewkb []byte, isGeography bool) ([]byte, error)`
+1. Read byte-order flag from `ewkb[0]`
+2. Read geometry type word bytes [1..4]
+3. If SRID flag (`0x20000000`) is set: strip bytes [5..8], clear flag in type word
+4. Call `mssqlclrgeo.WkbToUdtGeo(wkb, isGeography)`
+
+---
+
+## New files
+
+### `transformers/postgres.go`
+```go
+func NewPostgresTransformer(...) *Transformer {
+    // same signature as NewMssqlTransformer
+    // calls computePostgresTransformationPlan instead
+    // does NOT call computeStorageTransformationPlan
+}
+```
+
+### `computePostgresTransformationPlan` in `transformers/plan.go`
+Iterates `sourceColTypes` (from PG analyzer), applies inverse closures by system type.
+
+---
+
+## PostgreSQL table analyzer stubs to implement (`table_analyzers/postgres.go`)
+
+Required for PG-as-source partitioned extraction:
+
+### `EstimateTotalRows`
+```sql
+SELECT reltuples::bigint FROM pg_class
+  JOIN pg_namespace ON pg_namespace.oid = pg_class.relnamespace
+  WHERE pg_namespace.nspname = $schema AND pg_class.relname = $table
+```
+Fallback to `COUNT(*)` if `reltuples < 0`.
+
+### `QueryMaxMinFromColumn`
+```sql
+SELECT MIN("col"), MAX("col") FROM "schema"."table"
+```
+
+### `CalculatePartitionRanges`
+Use min/max from above + `rowsPerPartition` to compute boundaries. Mirror the logic from `MssqlTableAnalyzer.CalculatePartitionRanges`.
+
+---
+
+## Test cases
+
+### TC-1: `bigEndianToMssqlUuid` — round-trip
+- Input: run `mssqlUuidToBigEndian` on a known 16-byte MSSQL UUID → produces PG UUID
+- Assert: `bigEndianToMssqlUuid(pgUUID)` == original MSSQL UUID bytes
+- Also assert nil input → nil output (no panic)
+
+### TC-2: `bigEndianToMssqlUuid` — known vector
+- Input: `[0x6b,0xa7,0xb8,0x10, 0x9d,0xad, 0x11,0xd1, 0x80,0xb4,0x00,0xc0,0x4f,0xd4,0x30,0xc8]` (RFC 4122 nil UUID variant)
+- Assert: bytes [0-3] are reversed, [4-5] reversed, [6-7] reversed, [8-15] identical
+
+### TC-3: `ewkbToMssqlGeo` — geometry round-trip
+- Input: generate a polygon via `go-geom` + `wkb.Marshal` → plain WKB
+- Forward: run `wkbToEwkbWithSrid` → EWKB
+- Inverse: run `ewkbToMssqlGeo(ewkb, false)` → CLR/UDT bytes
+- Assert: no error, output is non-empty `[]byte`
+
+### TC-4: `ewkbToMssqlGeo` — nil input
+- Input: nil
+- Assert: returns nil, nil (no panic)
+
+### TC-5: `ewkbToMssqlGeo` — EWKB without SRID flag
+- Input: plain WKB (no SRID flag set)
+- Assert: function still calls `WkbToUdtGeo` and returns without error
+
+### TC-6: Transformer factory selection
+- Given `SourceDbType == "postgres"` → `NewPostgresTransformer` is selected
+- Given `SourceDbType == "sqlserver"` → `NewMssqlTransformer` is selected
+
+---
+
+## Files changed (summary)
+
+1. `cmd/go_migrate/process.go` — transformer factory branch
+2. `cmd/go_migrate/main.go` — analyzer selection branch
+3. `internal/app/etl/transformers/utils.go` — 2 new functions
+4. `internal/app/etl/transformers/plan.go` — `computePostgresTransformationPlan`
+5. `internal/app/etl/transformers/postgres.go` *(new)*
+6. `internal/app/etl/table_analyzers/postgres.go` — 3 stub implementations

scripts/az-blob/main.go

@@ -0,0 +1,44 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"math/rand"
+	"sync"
+
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/azure"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
+)
+
+func main() {
+	cfg := config.App.AzureStorage
+	containerName := cfg.Container
+
+	client, err := azure.NewClient(cfg)
+	if err != nil {
+		log.Fatalf("Error creando cliente: %v", err)
+	}
+	ctx := context.Background()
+
+	var wg sync.WaitGroup
+
+	for i := 1; i <= 10; i++ {
+		wg.Add(1)
+		go func(id int) {
+			defer wg.Done()
+
+			blobName := fmt.Sprintf("%sarchivo-%d.txt", cfg.Prefix, id)
+			content := fmt.Sprintf("Contenido aleatorio: %d", rand.Intn(100000))
+
+			err := client.UploadBuffer(ctx, containerName, blobName, []byte(content))
+			if err != nil {
+				log.Printf("Fallo al subir %s: %v", blobName, err)
+			} else {
+				fmt.Printf("Subido exitosamente: %s\n", blobName)
+			}
+		}(i)
+	}
+
+	wg.Wait()
+}

scripts/config-parser/main.go

@@ -0,0 +1,30 @@
+package main
+
+import (
+	"flag"
+
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
+	log "github.com/sirupsen/logrus"
+)
+
+func main() {
+	log.SetLevel(log.DebugLevel)
+
+	configPath := flag.String("config", "", "path to migration config file")
+	flag.Parse()
+
+	if flag.NArg() > 1 {
+		log.Fatalf("only one config file path is allowed")
+	}
+
+	if *configPath == "" && flag.NArg() == 1 {
+		*configPath = flag.Arg(0)
+	}
+
+	migrationConfig, err := config.ReadMigrationConfig(*configPath)
+	if err != nil {
+		log.Fatalf("error leyendo configuracion: %v", err)
+	}
+
+	log.Debugf("Config: %+v", migrationConfig)
+}

scripts/mssql-copy-in/main.go

@@ -12,11 +12,9 @@ import (
 )
 
 const (
-	totalRows int    = 1_000_000
+	totalRows int = 2_000_000
-	chunkSize int    = 50_000
+	chunkSize int = 5000
-	schema    string = "Cartografia"
+	queueSize int = 8
-	table     string = "MANZANA"
-	queueSize int    = 4
 )
 
 func main() {
@@ -42,6 +40,14 @@ func main() {
 		seedManzanas(ctx, db)
 	})
 
+	// wgSeed.Go(func() {
+	// 	seedPuertos(ctx, db)
+	// })
+
+	// wgSeed.Go(func() {
+	// 	seedSiteHolderAttach(ctx, db)
+	// })
+
 	wgSeed.Wait()
 }
 

scripts/mssql-copy-in/puerto.go

@@ -0,0 +1,225 @@
+package main
+
+import (
+	"context"
+	"database/sql"
+	"math/rand"
+	"time"
+
+	log "github.com/sirupsen/logrus"
+)
+
+func seedPuertos(ctx context.Context, db *sql.DB) {
+	rowsChan := make(chan []UnknownRowValues, queueSize)
+
+	// Column names for PUERTO table (excluding ID_PUERTO which is IDENTITY)
+	colNames := []string{
+		"ID_EQUIPO",
+		"ID_TERMINAL",
+		"ID_TIPO_EQUIPO",
+		"ID_PROYECTO_RESERVA",
+		"ID_TIPO_PUERTO",
+		"NUMERO",
+		"CODIGO",
+		"ESTADO",
+		"FECHA_ALTA",
+		"FECHA_ACT",
+		"ID_SITE_HOLDER",
+		"ID_PROYECTO_RESERVA_INICIAL",
+		"ID_DIRECCION",
+		"ID_TIPO_PUERTO_MEMORY",
+	}
+
+	// Start the data generator goroutine
+	go generatePuertoRows(ctx, totalRows, chunkSize, rowsChan)
+
+	// Load rows into MSSQL
+	job := MigrationJob{
+		Schema: "Red",
+		Table:  "PUERTO",
+	}
+
+	if err := loadRowsMssql(ctx, job, colNames, db, rowsChan); err != nil {
+		log.Fatal("Error loading PUERTO rows: ", err)
+	}
+
+	log.Info("PUERTO data generation and loading completed successfully")
+}
+
+// generatePuertoRows creates random row data for the PUERTO table and sends it through a channel
+func generatePuertoRows(
+	ctx context.Context,
+	totalRows int,
+	chunkSize int,
+	out chan<- []UnknownRowValues,
+) {
+	defer close(out)
+
+	rowsGenerated := 0
+	currentChunk := make([]UnknownRowValues, 0, chunkSize)
+
+	for range totalRows {
+		row := generatePuertoRow()
+		currentChunk = append(currentChunk, row)
+		rowsGenerated++
+
+		// Send chunk when it reaches the desired size
+		if len(currentChunk) == chunkSize {
+			select {
+			case out <- currentChunk:
+				log.Debugf("Sent PUERTO chunk with %d rows", len(currentChunk))
+			case <-ctx.Done():
+				log.Info("Context cancelled, stopping PUERTO row generation")
+				return
+			}
+			currentChunk = make([]UnknownRowValues, 0, chunkSize)
+		}
+
+		if rowsGenerated%100_000 == 0 {
+			logPuertoSampleRow(rowsGenerated, row)
+		}
+	}
+
+	// Send remaining rows
+	if len(currentChunk) > 0 {
+		select {
+		case out <- currentChunk:
+			log.Debugf("Sent final PUERTO chunk with %d rows", len(currentChunk))
+		case <-ctx.Done():
+			log.Info("Context cancelled, stopping PUERTO row generation")
+		}
+	}
+
+	log.Infof("Finished generating %d PUERTO rows", rowsGenerated)
+}
+
+// generatePuertoRow creates a single random row for the PUERTO table
+func generatePuertoRow() UnknownRowValues {
+	dateLowerLimit, _ := time.Parse(time.RFC3339, "2020-12-31T23:59:59Z")
+	dateUpperLimit, _ := time.Parse(time.RFC3339, "2025-12-31T23:59:59Z")
+
+	// Required columns
+	idEquipo := rand.Intn(10000) + 1    // ID_EQUIPO (1-10000)
+	idTipoEquipo := rand.Intn(100) + 1  // ID_TIPO_EQUIPO (1-100)
+	idTipoPuerto := rand.Intn(50) + 1   // ID_TIPO_PUERTO (1-50)
+	numero := rand.Intn(1000) + 1       // NUMERO (1-1000)
+	codigo := generateRandomString(100) // CODIGO: Random alphanumeric (up to 100 chars)
+
+	// Optional columns - randomly decide whether to include NULL or a value
+	var idTerminal any
+	if rand.Intn(2) == 0 {
+		idTerminal = rand.Intn(5000) + 1
+	} else {
+		idTerminal = nil
+	}
+
+	var idProyectoReserva any
+	if rand.Intn(2) == 0 {
+		idProyectoReserva = rand.Intn(1000) + 1
+	} else {
+		idProyectoReserva = nil
+	}
+
+	var estado any
+	if rand.Intn(2) == 0 {
+		estados := []string{"ACTIVO", "LIBRE", "DISPONIBLE", "MANTENIMIENTO", "RESERVADO"}
+		estado = estados[rand.Intn(len(estados))]
+	} else {
+		estado = nil
+	}
+
+	var fechaAlta any
+	if rand.Intn(2) == 0 {
+		fechaAlta = generateRandomTimestamp(dateLowerLimit, dateUpperLimit)
+	} else {
+		fechaAlta = nil
+	}
+
+	var fechaAct any
+	if rand.Intn(2) == 0 {
+		fechaAct = generateRandomTimestamp(dateLowerLimit, dateUpperLimit)
+	} else {
+		fechaAct = nil
+	}
+
+	var idSiteHolder any
+	if rand.Intn(2) == 0 {
+		idSiteHolder = rand.Intn(500) + 1
+	} else {
+		idSiteHolder = nil
+	}
+
+	var idProyectoReservaInicial any
+	if rand.Intn(2) == 0 {
+		idProyectoReservaInicial = rand.Intn(1000) + 1
+	} else {
+		idProyectoReservaInicial = nil
+	}
+
+	var idDireccion any
+	if rand.Intn(2) == 0 {
+		idDireccion = rand.Intn(100) + 1
+	} else {
+		idDireccion = nil
+	}
+
+	var idTipoPuertoMemory any
+	if rand.Intn(2) == 0 {
+		idTipoPuertoMemory = rand.Intn(50) + 1
+	} else {
+		idTipoPuertoMemory = nil
+	}
+
+	return UnknownRowValues{
+		idEquipo,
+		idTerminal,
+		idTipoEquipo,
+		idProyectoReserva,
+		idTipoPuerto,
+		numero,
+		codigo,
+		estado,
+		fechaAlta,
+		fechaAct,
+		idSiteHolder,
+		idProyectoReservaInicial,
+		idDireccion,
+		idTipoPuertoMemory,
+	}
+}
+
+func logPuertoSampleRow(id int, rowValues UnknownRowValues) {
+	log.Infof(`
+Sample row #%d:
+ID_EQUIPO (%T): %v
+ID_TERMINAL (%T): %v
+ID_TIPO_EQUIPO (%T): %v
+ID_PROYECTO_RESERVA (%T): %v
+ID_TIPO_PUERTO (%T): %v
+NUMERO (%T): %v
+CODIGO (%T): %v
+ESTADO (%T): %v
+FECHA_ALTA (%T): %v
+FECHA_ACT (%T): %v
+ID_SITE_HOLDER (%T): %v
+ID_PROYECTO_RESERVA_INICIAL (%T): %v
+ID_DIRECCION (%T): %v
+ID_TIPO_PUERTO_MEMORY (%T): %v
+`,
+		id,
+		rowValues[0], rowValues[0],
+		rowValues[1], rowValues[1],
+		rowValues[2], rowValues[2],
+		rowValues[3], rowValues[3],
+		rowValues[4], rowValues[4],
+		rowValues[5], rowValues[5],
+		rowValues[6], rowValues[6],
+		rowValues[7], rowValues[7],
+		rowValues[8], rowValues[8],
+		rowValues[9], rowValues[9],
+		rowValues[10], rowValues[10],
+		rowValues[11], rowValues[11],
+		rowValues[12], rowValues[12],
+		rowValues[13], rowValues[13],
+	)
+}

scripts/mssql-copy-in/seed-manzana.go

@@ -13,13 +13,18 @@ import (
 	log "github.com/sirupsen/logrus"
 )
 
+var manzanaJob = MigrationJob{
+	Schema: "Cartografia",
+	Table:  "MANZANA",
+}
+
 func getMaxGDBArchiveOid(ctx context.Context, db *sql.DB) (int, error) {
 	var maxOid sql.NullInt64
 
 	query := fmt.Sprintf(`
 		SELECT ISNULL(MAX(GDB_ARCHIVE_OID), 0)
 		FROM [%s].[%s]
-	`, schema, table)
+	`, manzanaJob.Schema, manzanaJob.Table)
 
 	err := db.QueryRowContext(ctx, query).Scan(&maxOid)
 	if err != nil && err != sql.ErrNoRows {
@@ -96,8 +101,7 @@ func generateManzanaRow(gdbArchiveOid int) UnknownRowValues {
 	fechaAct := generateRandomTimestamp(dateLowerLimit, dateUpperLimit)
 	shapeWKB := generateRandomPolygonWKB()
 	geoData := []byte{}
-	id := uuid.New()
+	globalID, _ := uuid.New().MarshalBinary()
-	globalID := id[:]
 	gdbFromDate := fechaAct
 	gdbToDate, _ := time.Parse(time.RFC3339, "9999-12-31T23:59:59Z")
 	objectID := gdbArchiveOid
@@ -211,12 +215,7 @@ func seedManzanas(ctx context.Context, db *sql.DB) error {
 		"OBJECTID",
 	}
 
-	job := MigrationJob{
+	if err := loadRowsMssql(ctx, manzanaJob, columns, db, rowsChan); err != nil {
-		Schema: schema,
-		Table:  table,
-	}
-
-	if err := loadRowsMssql(ctx, job, columns, db, rowsChan); err != nil {
 		return fmt.Errorf("Error loading rows (MANZANA): %w", err)
 	}
 

scripts/mssql-copy-in/site-holder-attach.go

@@ -0,0 +1,227 @@
+package main
+
+import (
+	"bytes"
+	"context"
+	"database/sql"
+	"fmt"
+	"math/rand"
+	"sync"
+	"time"
+
+	"github.com/google/uuid"
+	log "github.com/sirupsen/logrus"
+)
+
+var siteHolderAttachJob = MigrationJob{
+	Schema: "Infraestructura",
+	Table:  "SITE_HOLDER__ATTACH",
+}
+
+func seedSiteHolderAttach(ctx context.Context, db *sql.DB) error {
+	maxOid, err := getMaxGDBArchiveOidForAttach(ctx, db)
+	if err != nil {
+		log.Fatal("Error getting max GDB_ARCHIVE_OID: ", err)
+	}
+
+	log.Infof("Starting SITE_HOLDER__ATTACH data generation from GDB_ARCHIVE_OID: %d", maxOid+1)
+
+	rowsChan := make(chan []UnknownRowValues, queueSize)
+
+	var wgRowGenerator sync.WaitGroup
+
+	wgRowGenerator.Go(func() {
+		generateSiteHolderAttachRows(ctx, maxOid, totalRows, chunkSize, rowsChan)
+	})
+
+	columns := []string{
+		"GDB_ARCHIVE_OID",
+		"REL_GLOBALID",
+		"CONTENT_TYPE",
+		"ATT_NAME",
+		"DATA_SIZE",
+		"DATA",
+		"GLOBALID",
+		"GDB_FROM_DATE",
+		"GDB_TO_DATE",
+		"ATTACHMENTID",
+	}
+
+	if err := loadRowsMssql(ctx, siteHolderAttachJob, columns, db, rowsChan); err != nil {
+		return fmt.Errorf("Error loading rows (SITE_HOLDER__ATTACH): %w", err)
+	}
+
+	log.Info("Data generation and loading completed successfully (SITE_HOLDER__ATTACH)")
+	wgRowGenerator.Wait()
+
+	return nil
+}
+
+func getMaxGDBArchiveOidForAttach(ctx context.Context, db *sql.DB) (int, error) {
+	var maxOid sql.NullInt64
+
+	query := fmt.Sprintf(`
+		SELECT ISNULL(MAX(GDB_ARCHIVE_OID), 0)
+		FROM [%s].[%s]
+	`, siteHolderAttachJob.Schema, siteHolderAttachJob.Table)
+
+	err := db.QueryRowContext(ctx, query).Scan(&maxOid)
+	if err != nil && err != sql.ErrNoRows {
+		return 0, err
+	}
+
+	if !maxOid.Valid {
+		return 0, nil
+	}
+
+	return int(maxOid.Int64), nil
+}
+
+func generateSiteHolderAttachRows(
+	ctx context.Context,
+	startOid int,
+	totalRows int,
+	chunkSize int,
+	out chan<- []UnknownRowValues,
+) {
+	defer close(out)
+
+	rowsGenerated := 0
+	currentChunk := make([]UnknownRowValues, 0, chunkSize)
+
+	for i := range totalRows {
+		gdbArchiveOid := startOid + i + 1
+		row := generateSiteHolderAttachRow(gdbArchiveOid)
+		currentChunk = append(currentChunk, row)
+		rowsGenerated++
+
+		if len(currentChunk) == chunkSize {
+			select {
+			case out <- currentChunk:
+				log.Debugf("Sent SITE_HOLDER__ATTACH chunk with %d rows", len(currentChunk))
+			case <-ctx.Done():
+				log.Info("Context cancelled, stopping SITE_HOLDER__ATTACH row generation")
+				return
+			}
+			currentChunk = make([]UnknownRowValues, 0, chunkSize)
+		}
+
+		if rowsGenerated%100_000 == 0 {
+			logSiteHolderAttachSampleRow(rowsGenerated, row)
+		}
+	}
+
+	if len(currentChunk) > 0 {
+		select {
+		case out <- currentChunk:
+			log.Debugf("Sent final SITE_HOLDER__ATTACH chunk with %d rows", len(currentChunk))
+		case <-ctx.Done():
+			log.Info("Context cancelled, stopping SITE_HOLDER__ATTACH row generation")
+		}
+	}
+
+	log.Infof("Finished generating %d SITE_HOLDER__ATTACH rows", rowsGenerated)
+}
+
+func generateSiteHolderAttachRow(gdbArchiveOid int) UnknownRowValues {
+	dateLowerLimit, _ := time.Parse(time.RFC3339, "2020-12-31T23:59:59Z")
+	dateUpperLimit, _ := time.Parse(time.RFC3339, "2025-12-31T23:59:59Z")
+
+	relGlobalID, _ := uuid.New().MarshalBinary()
+	contentType := generateRandomContentType()
+	attName := generateRandomAttachmentName()
+	binaryData := generateRandomBinaryContent()
+	dataSize := len(binaryData)
+	globalID, _ := uuid.New().MarshalBinary()
+	gdbFromDate := generateRandomTimestamp(dateLowerLimit, dateUpperLimit)
+	gdbToDate, _ := time.Parse(time.RFC3339, "9999-12-31T23:59:59Z")
+	attachmentID := rand.Intn(10000) + 1
+
+	return UnknownRowValues{
+		gdbArchiveOid,
+		relGlobalID,
+		contentType,
+		attName,
+		dataSize,
+		binaryData,
+		globalID,
+		gdbFromDate,
+		gdbToDate,
+		attachmentID,
+	}
+}
+
+func generateRandomContentType() string {
+	contentTypes := []string{
+		"text/plain",
+		"application/pdf",
+		"image/jpeg",
+		"image/png",
+		"application/msword",
+		"application/vnd.openxmlformats-officedocument.wordprocessingml.document",
+		"text/csv",
+		"application/json",
+	}
+	return contentTypes[rand.Intn(len(contentTypes))]
+}
+
+func generateRandomAttachmentName() string {
+	extensions := []string{".txt", ".pdf", ".jpg", ".png", ".doc", ".docx", ".csv", ".json"}
+	baseName := generateRandomString(20)
+	extension := extensions[rand.Intn(len(extensions))]
+	return baseName + extension
+}
+
+func generateRandomBinaryContent() []byte {
+	sizeOptions := []int{100, 500, 1000, 5000, 10000, 50000, 100000}
+	size := sizeOptions[rand.Intn(len(sizeOptions))]
+
+	var buf bytes.Buffer
+
+	lineCount := rand.Intn(size/50) + 1
+	for range lineCount {
+		line := generateRandomString(rand.Intn(80) + 20)
+		buf.WriteString(line)
+		buf.WriteString("\n")
+	}
+
+	for buf.Len() < size {
+		randomText := generateRandomString(rand.Intn(100) + 50)
+		buf.WriteString(randomText)
+		buf.WriteString("\n")
+	}
+
+	result := buf.Bytes()
+	if len(result) > size {
+		result = result[:size]
+	}
+
+	return result
+}
+
+func logSiteHolderAttachSampleRow(id int, rowValues UnknownRowValues) {
+	dataBytes := rowValues[5].([]byte)
+	log.Infof(`
+Sample SITE_HOLDER__ATTACH row #%d:
+GDB_ARCHIVE_OID: %v
+REL_GLOBALID: [binary UUID]
+CONTENT_TYPE: %v
+ATT_NAME: %v
+DATA_SIZE: %v
+DATA: [%d bytes of binary content]
+GLOBALID: [binary UUID]
+GDB_FROM_DATE: %v
+GDB_TO_DATE: %v
+ATTACHMENTID: %v
+`,
+		id,
+		rowValues[0],
+		rowValues[2],
+		rowValues[3],
+		rowValues[4],
+		len(dataBytes),
+		rowValues[7],
+		rowValues[8],
+		rowValues[9],
+	)
+}

scripts/pg-info-test/main.go

@@ -8,13 +8,32 @@ import (
 	"time"
 
 	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
-	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/db"
 	"github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgtype"
 	"github.com/jackc/pgx/v5/pgxpool"
 	log "github.com/sirupsen/logrus"
 )
 
+func Connect(ctx context.Context, dbURL string) (*pgxpool.Pool, error) {
+	pool, err := pgxpool.New(ctx, dbURL)
+	if err != nil {
+		return nil, fmt.Errorf("unable to connect to database: %w", err)
+	}
+
+	if err := pool.Ping(ctx); err != nil {
+		pool.Close()
+		return nil, fmt.Errorf("unable to ping database: %w", err)
+	}
+
+	return pool, nil
+}
+
+func Close(pool *pgxpool.Pool) {
+	if pool != nil {
+		pool.Close()
+	}
+}
+
 func main() {
 	log.SetFormatter(&log.TextFormatter{
 		FullTimestamp:   true,
@@ -27,8 +46,8 @@ func main() {
 	ctxSource, cancel := context.WithTimeout(context.Background(), 20*time.Second)
 	defer cancel()
 
-	sourcePool, err := db.Connect(ctxSource, config.App.SourceDbUrl)
+	sourcePool, err := Connect(ctxSource, config.App.SourceDbUrl)
-	defer db.Close(sourcePool)
+	defer Close(sourcePool)
 	if err != nil {
 		log.Fatal(err)
 	}
@@ -37,8 +56,8 @@ func main() {
 	ctxTarget, cancel := context.WithTimeout(context.Background(), 20*time.Second)
 	defer cancel()
 
-	targetPool, err := db.Connect(ctxTarget, config.App.TargetDbUrl)
+	targetPool, err := Connect(ctxTarget, config.App.TargetDbUrl)
-	defer db.Close(targetPool)
+	defer Close(targetPool)
 	if err != nil {
 		log.Fatal(err)
 	}