refactor: replace specific extractor implementations with a generic extractor; remove mssql and postgres extractor files

cmd/go_migrate/main.go

@@ -118,7 +118,7 @@ func processMigrationJobs(
 
 	sourceTableAnalyzer := table_analyzers.NewMssqlTableAnalyzer(sourceDb)
 	targetTableAnalyzer := table_analyzers.NewPostgresTableAnalyzer(targetDb)
-	extractor := extractors.NewMssqlExtractor(sourceDb)
+	extractor := extractors.NewExtractor(sourceDb)
 	loader := loaders.NewGenericLoader(targetDb)
 
 	var azureClient *azure.Client

cmd/go_migrate/process.go

@@ -39,7 +39,7 @@ func processMigrationJob(
 	targetDbWrapper dbwrapper.DbWrapper,
 	sourceTableAnalyzer etl.TableAnalyzer,
 	targetTableAnalyzer etl.TableAnalyzer,
-	extractor etl.Extractor,
+	extractor extractors.GenericExtractor,
 	azureClient *azure.Client,
 	loader etl.Loader,
 	job config.Job,
@@ -155,9 +155,8 @@ func processMigrationJob(
 
 	for range maxExtractors {
 		wgExtractors.Go(func() {
-			extractors.Consume(
+			extractor.Consume(
 				localCtx,
-				extractor,
 				job.SourceTable,
 				sourceColTypes,
 				job.BatchSize,

internal/app/etl/extractors/main.go

@@ -12,13 +12,144 @@ import (
 	"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"
-	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/etl"
+	dbwrapper "git.ksdemosapps.com/kylesoda/go-migrate/internal/app/db-wrapper"
 	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/models"
+	"github.com/google/uuid"
 )
 
-func Consume(
+type GenericExtractor struct {
+	db dbwrapper.DbWrapper
+}
+
+func NewExtractor(db dbwrapper.DbWrapper) GenericExtractor {
+	return GenericExtractor{db: db}
+}
+
+func errorFromLastRow(
+	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,
+) (int, error) {
+	rowsRead := 0
+	query := dbwrapper.ExtractionQuery{
+		Schema:     tableInfo.Schema,
+		Table:      tableInfo.Table,
+		PrimaryKey: tableInfo.PrimaryKey,
+		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,
+		},
+	}
+
+	rows, err := ex.db.QueryFromObject(ctx, query)
+
+	if err != nil {
+		return rowsRead, &custom_errors.ExtractorError{Partition: partition, HasLastId: false, Msg: err.Error()}
+	}
+	defer rows.Close()
+
+	batchRows := make([]models.UnknownRowValues, 0, batchSize)
+
+	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, &custom_errors.ExtractorError{Partition: partition, HasLastId: false, Msg: err.Error()}
+			}
+
+			lastRow := batchRows[len(batchRows)-1]
+
+			select {
+			case chBatchesOut <- models.Batch{Id: uuid.New(), PartitionId: partition.Id, Rows: batchRows, RetryCounter: 0}:
+			case <-ctx.Done():
+				return rowsRead, ctx.Err()
+			}
+
+			return rowsRead, errorFromLastRow(lastRow, indexPrimaryKey, partition, err)
+		}
+		rowsRead++
+
+		batchRows = append(batchRows, rowValues)
+		if len(batchRows) >= batchSize {
+			select {
+			case chBatchesOut <- models.Batch{Id: uuid.New(), PartitionId: partition.Id, Rows: batchRows, RetryCounter: 0}:
+			case <-ctx.Done():
+				return rowsRead, ctx.Err()
+			}
+
+			batchRows = make([]models.UnknownRowValues, 0, batchSize)
+		}
+	}
+
+	if err := rows.Err(); err != nil {
+		if errors.Is(err, ctx.Err()) {
+			return rowsRead, ctx.Err()
+		}
+
+		if len(batchRows) > 0 {
+			lastRow := batchRows[len(batchRows)-1]
+			return rowsRead, errorFromLastRow(lastRow, indexPrimaryKey, partition, err)
+		}
+
+		return rowsRead, &custom_errors.ExtractorError{Partition: partition, HasLastId: false, Msg: err.Error()}
+	}
+
+	if len(batchRows) > 0 {
+		select {
+		case chBatchesOut <- models.Batch{Id: uuid.New(), PartitionId: partition.Id, Rows: batchRows, RetryCounter: 0}:
+		case <-ctx.Done():
+			return rowsRead, ctx.Err()
+		}
+	}
+
+	return rowsRead, nil
+}
+
+func (ex *GenericExtractor) Consume(
 	ctx context.Context,
-	extractor etl.Extractor,
 	tableInfo config.SourceTableInfo,
 	columns []models.ColumnType,
 	batchSize int,
@@ -59,7 +190,7 @@ func Consume(
 				return
 			}
 
-			rowsReadResult, err := extractor.ProcessPartition(
+			rowsReadResult, err := ex.ProcessPartition(
 				ctx,
 				tableInfo,
 				columns,
@@ -101,30 +232,3 @@ func Consume(
 		}
 	}
 }
-
-func errorFromLastRow(
-	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(),
-	}
-}

internal/app/etl/extractors/mssql.go

@@ -1,180 +0,0 @@
-package extractors
-
-import (
-	"context"
-	"database/sql"
-	"errors"
-	"fmt"
-	"strings"
-
-	"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/etl"
-	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/models"
-	"github.com/google/uuid"
-)
-
-type MssqlExtractor struct {
-	db dbwrapper.DbWrapper
-}
-
-func NewMssqlExtractor(db dbwrapper.DbWrapper) etl.Extractor {
-	return &MssqlExtractor{db: db}
-}
-
-func buildExtractQueryMssql(
-	tableInfo config.SourceTableInfo,
-	columns []models.ColumnType,
-	includeRange bool,
-	isMinInclusive bool,
-	isMaxInclusive bool,
-	hasMin bool,
-	hasMax 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.Type() == "GEOMETRY" {
-				fmt.Fprintf(&sbQuery, ".STAsBinary() AS [%s]", col.Name())
-			}
-
-			if i < len(columns)-1 {
-				sbQuery.WriteString(", ")
-			}
-		}
-	}
-
-	fmt.Fprintf(&sbQuery, " FROM [%s].[%s]", tableInfo.Schema, tableInfo.Table)
-
-	if includeRange && (hasMin || hasMax) {
-		sbQuery.WriteString(" WHERE ")
-
-		if hasMin {
-			fmt.Fprintf(&sbQuery, "[%s]", tableInfo.PrimaryKey)
-			if isMinInclusive {
-				sbQuery.WriteString(" >=")
-			} else {
-				sbQuery.WriteString(" >")
-			}
-			sbQuery.WriteString(" @min")
-		}
-
-		if hasMin && hasMax {
-			sbQuery.WriteString(" AND ")
-		}
-
-		if hasMax {
-			fmt.Fprintf(&sbQuery, "[%s]", tableInfo.PrimaryKey)
-			if isMaxInclusive {
-				sbQuery.WriteString(" <=")
-			} else {
-				sbQuery.WriteString(" <")
-			}
-			sbQuery.WriteString(" @max")
-		}
-	}
-
-	fmt.Fprintf(&sbQuery, " ORDER BY [%s] ASC", tableInfo.PrimaryKey)
-
-	return sbQuery.String()
-}
-
-func (mssqlEx *MssqlExtractor) ProcessPartition(
-	ctx context.Context,
-	tableInfo config.SourceTableInfo,
-	columns []models.ColumnType,
-	batchSize int,
-	partition models.Partition,
-	indexPrimaryKey int,
-	chBatchesOut chan<- models.Batch,
-) (int, error) {
-	hasMin := partition.HasRange && partition.Range.Min > 0
-	hasMax := partition.HasRange && partition.Range.Max > 0
-	query := buildExtractQueryMssql(tableInfo, columns, partition.HasRange, partition.Range.IsMinInclusive, partition.Range.IsMaxInclusive, hasMin, hasMax)
-
-	var queryArgs []any
-	if hasMin {
-		queryArgs = append(queryArgs, sql.Named("min", partition.Range.Min))
-	}
-	if hasMax {
-		queryArgs = append(queryArgs, sql.Named("max", partition.Range.Max))
-	}
-
-	rowsRead := 0
-	rows, err := mssqlEx.db.Query(ctx, query, queryArgs...)
-	if err != nil {
-		return rowsRead, &custom_errors.ExtractorError{Partition: partition, HasLastId: false, Msg: err.Error()}
-	}
-	defer rows.Close()
-
-	batchRows := make([]models.UnknownRowValues, 0, batchSize)
-
-	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, &custom_errors.ExtractorError{Partition: partition, HasLastId: false, Msg: err.Error()}
-			}
-
-			lastRow := batchRows[len(batchRows)-1]
-
-			select {
-			case chBatchesOut <- models.Batch{Id: uuid.New(), PartitionId: partition.Id, Rows: batchRows, RetryCounter: 0}:
-			case <-ctx.Done():
-				return rowsRead, ctx.Err()
-			}
-
-			return rowsRead, errorFromLastRow(lastRow, indexPrimaryKey, partition, err)
-		}
-		rowsRead++
-
-		batchRows = append(batchRows, rowValues)
-		if len(batchRows) >= batchSize {
-			select {
-			case chBatchesOut <- models.Batch{Id: uuid.New(), PartitionId: partition.Id, Rows: batchRows, RetryCounter: 0}:
-			case <-ctx.Done():
-				return rowsRead, ctx.Err()
-			}
-
-			batchRows = make([]models.UnknownRowValues, 0, batchSize)
-		}
-
-	}
-
-	if err := rows.Err(); err != nil {
-		if errors.Is(err, ctx.Err()) {
-			return rowsRead, ctx.Err()
-		}
-
-		if len(batchRows) > 0 {
-			lastRow := batchRows[len(batchRows)-1]
-			return rowsRead, errorFromLastRow(lastRow, indexPrimaryKey, partition, err)
-		}
-
-		return rowsRead, &custom_errors.ExtractorError{Partition: partition, HasLastId: false, Msg: err.Error()}
-	}
-
-	if len(batchRows) > 0 {
-		select {
-		case chBatchesOut <- models.Batch{Id: uuid.New(), PartitionId: partition.Id, Rows: batchRows, RetryCounter: 0}:
-		case <-ctx.Done():
-			return rowsRead, ctx.Err()
-		}
-	}
-
-	return rowsRead, nil
-}

internal/app/etl/extractors/postgres.go

@@ -1,157 +0,0 @@
-package extractors
-
-import (
-	"context"
-	"fmt"
-	"strings"
-
-	"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/etl"
-	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/models"
-	"github.com/google/uuid"
-)
-
-type PostgresExtractor struct {
-	db dbwrapper.DbWrapper
-}
-
-func NewPostgresExtractor(db dbwrapper.DbWrapper) etl.Extractor {
-	return &PostgresExtractor{db: db}
-}
-
-func buildExtractQueryPostgres(
-	sourceDbInfo config.SourceTableInfo,
-	columns []models.ColumnType,
-	includeRange bool,
-	isMinInclusive bool,
-	isMaxInclusive bool,
-	hasMin bool,
-	hasMax bool,
-) string {
-	var sbColumns strings.Builder
-
-	if len(columns) == 0 {
-		sbColumns.WriteString("*")
-	} else {
-		for i, col := range columns {
-			if col.Type() == "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(", ")
-			}
-		}
-	}
-
-	query := fmt.Sprintf(`SELECT %s FROM "%s"."%s"`, sbColumns.String(), sourceDbInfo.Schema, sourceDbInfo.Table)
-
-	if includeRange && (hasMin || hasMax) {
-		query += " WHERE "
-		paramIdx := 1
-
-		if hasMin {
-			query += fmt.Sprintf(`"%s"`, sourceDbInfo.PrimaryKey)
-			if isMinInclusive {
-				query += " >="
-			} else {
-				query += " >"
-			}
-			query += fmt.Sprintf(" $%d", paramIdx)
-			paramIdx++
-		}
-
-		if hasMin && hasMax {
-			query += " AND "
-		}
-
-		if hasMax {
-			query += fmt.Sprintf(`"%s"`, sourceDbInfo.PrimaryKey)
-			if isMaxInclusive {
-				query += " <="
-			} else {
-				query += " <"
-			}
-			query += fmt.Sprintf(" $%d", paramIdx)
-		}
-	}
-
-	query += fmt.Sprintf(` ORDER BY "%s" ASC`, sourceDbInfo.PrimaryKey)
-
-	return query
-}
-
-func (postgresEx *PostgresExtractor) ProcessPartition(
-	ctx context.Context,
-	tableInfo config.SourceTableInfo,
-	columns []models.ColumnType,
-	batchSize int,
-	partition models.Partition,
-	indexPrimaryKey int,
-	chBatchesOut chan<- models.Batch,
-) (int, error) {
-	hasMin := partition.HasRange && partition.Range.Min > 0
-	hasMax := partition.HasRange && partition.Range.Max > 0
-	query := buildExtractQueryPostgres(tableInfo, columns, partition.HasRange, partition.Range.IsMinInclusive, partition.Range.IsMaxInclusive, hasMin, hasMax)
-
-	var queryArgs []any
-	if hasMin {
-		queryArgs = append(queryArgs, partition.Range.Min)
-	}
-	if hasMax {
-		queryArgs = append(queryArgs, partition.Range.Max)
-	}
-
-	rowsRead := 0
-	rows, err := postgresEx.db.Query(ctx, query, queryArgs...)
-	if err != nil {
-		return rowsRead, &custom_errors.ExtractorError{Partition: partition, HasLastId: false, Msg: err.Error()}
-	}
-	defer rows.Close()
-
-	batchRows := make([]models.UnknownRowValues, 0, batchSize)
-
-	for rows.Next() {
-		values, err := rows.Values()
-		if err != nil {
-			return rowsRead, &custom_errors.ExtractorError{Partition: partition, HasLastId: false, Msg: err.Error()}
-		}
-		rowsRead++
-
-		batchRows = append(batchRows, values)
-
-		if len(batchRows) >= batchSize {
-			select {
-			case chBatchesOut <- models.Batch{Id: uuid.New(), PartitionId: partition.Id, Rows: batchRows, RetryCounter: 0}:
-			case <-ctx.Done():
-				return rowsRead, ctx.Err()
-			}
-
-			batchRows = make([]models.UnknownRowValues, 0, batchSize)
-		}
-	}
-
-	if err := rows.Err(); err != nil {
-		return rowsRead, &custom_errors.ExtractorError{Partition: partition, HasLastId: false, Msg: err.Error()}
-	}
-
-	if len(batchRows) > 0 {
-		select {
-		case chBatchesOut <- models.Batch{Id: uuid.New(), PartitionId: partition.Id, Rows: batchRows, RetryCounter: 0}:
-		case <-ctx.Done():
-			return rowsRead, nil
-		}
-	}
-
-	return rowsRead, nil
-}