feat: add MSSQL extractor and transformer implementations for improved data migration

cmd/go_migrate/process.go

@@ -10,6 +10,7 @@ import (
 	"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/extractor"
+	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/etl/transformer"
 	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/models"
 	"github.com/jackc/pgx/v5/pgxpool"
 
@@ -60,6 +61,9 @@ func processMigrationJob(
 	var wgTransformers sync.WaitGroup
 	var wgLoaders sync.WaitGroup
 
+	mssqlExtractor := extractor.NewMssqlExtractor(sourceDb)
+	mssqlToPostgresTransformer := transformer.NewMssqlTransformer()
+
 	go func() {
 		if err := custom_errors.JobErrorHandler(jobCtx, chJobErrors); err != nil {
 			cancel()
@@ -73,11 +77,9 @@ func processMigrationJob(
 	maxExtractors := min(job.MaxExtractors, len(batches))
 	log.Infof("Starting %d extractor(s)...", maxExtractors)
 
-	exMssql := extractor.NewMssqlExtractor(sourceDb)
-
 	for range maxExtractors {
 		wgExtractors.Go(func() {
-			exMssql.Exec(
+			mssqlExtractor.Exec(
 				jobCtx,
 				job.SourceTable,
 				sourceColTypes,
@@ -103,7 +105,14 @@ func processMigrationJob(
 
 	for range maxExtractors {
 		wgTransformers.Go(func() {
-			transformRowsMssql(jobCtx, sourceColTypes, chChunksRaw, chChunksTransformed, chJobErrors, &wgActiveChunks)
+			mssqlToPostgresTransformer.Exec(
+				jobCtx,
+				sourceColTypes,
+				chChunksRaw,
+				chChunksTransformed,
+				chJobErrors,
+				&wgActiveChunks,
+			)
 		})
 	}