feat: streamline data extraction from MSSQL and Postgres, add UUID transformation

cmd/go_migrate/process.go

@@ -23,16 +23,11 @@ func processMigrationJob(sourceDb *sql.DB, targetDb *pgxpool.Pool, job Migration
 
 	chRowsExtract := make(chan []UnknownRowValues, QueueSize)
 	mssqlContext := context.Background()
-	var wgMssqlExtractors sync.WaitGroup
 
-	wgMssqlExtractors.Go(func() {
+	go func() {
 		if err := extractFromMssql(mssqlContext, job, sourceColTypes, ChunkSize, sourceDb, chRowsExtract); err != nil {
 			log.Error("Unexpected error extrating data from mssql: ", err)
 		}
-	})
-
-	go func() {
-		wgMssqlExtractors.Wait()
 		close(chRowsExtract)
 	}()
 
@@ -44,16 +39,11 @@ func processMigrationJob(sourceDb *sql.DB, targetDb *pgxpool.Pool, job Migration
 
 	chRowsExtractPostgres := make(chan []UnknownRowValues, QueueSize)
 	postgresContext := context.Background()
-	var wgPostgresExtractors sync.WaitGroup
 
-	wgPostgresExtractors.Go(func() {
+	go func() {
 		if err := extractFromPostgres(postgresContext, job, sourceColTypes, ChunkSize, targetDb, chRowsExtractPostgres); err != nil {
 			log.Error("Unexpected error extrating data from postgres: ", err)
 		}
-	})
-
-	go func() {
-		wgPostgresExtractors.Wait()
 		close(chRowsExtractPostgres)
 	}()
 
@@ -78,6 +68,15 @@ func transformRows(job MigrationJob, columns []ColumnType, driver string, in <-c
 		log.Debugf("Chunk received (%s), transforming...", driver)
 
 		for i, rowValues := range rows {
+			for i, col := range columns {
+				value := rowValues[i]
+				if col.SystemType() == "uniqueidentifier" && driver == "sqlserver" {
+					if b, ok := value.([]byte); ok {
+						rowValues[i] = mssqlUuidToBigEndian(b)
+					}
+				}
+			}
+
 			if i%100 == 0 {
 				logSampleRow(job, columns, rowValues, fmt.Sprintf("row %d", i))
 			}
@@ -91,3 +90,16 @@ func logSampleRow(job MigrationJob, columns []ColumnType, rowValues UnknownRowVa
 		log.Infof("%s: %v", col.Name(), rowValues[i])
 	}
 }
+
+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
+}