feat: implement MSSQL bulk loading functionality with transaction handling

cmd/go_migrate/loader.go

@@ -2,15 +2,18 @@ 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...")
 
@@ -51,8 +54,72 @@ func loadRowsPostgres(ctx context.Context, job MigrationJob, columns []ColumnTyp
 		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)
+		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