move merge to own tx

flow/connectors/snowflake/snowflake.go

@@ -769,8 +769,7 @@ func (c *SnowflakeConnector) NormalizeRecords(req *model.NormalizeRecordsRequest
 				tableNametoUnchangedToastCols[tableName],
 				getRawTableIdentifier(req.FlowJobName),
 				syncBatchID, normalizeBatchID,
-				req,
-				normalizeRecordsTx)
+				req)
 			if err != nil {
 				log.WithFields(log.Fields{
 					"flowName": req.FlowJobName,
@@ -987,7 +986,6 @@ func (c *SnowflakeConnector) generateAndExecuteMergeStatement(
 	syncBatchID int64,
 	normalizeBatchID int64,
 	normalizeReq *model.NormalizeRecordsRequest,
-	normalizeRecordsTx *sql.Tx,
 ) (int64, error) {
 	normalizedTableSchema := c.tableSchemaMapping[destinationTableIdentifier]
 	columnNames := maps.Keys(normalizedTableSchema.Columns)
@@ -1093,16 +1091,28 @@ func (c *SnowflakeConnector) generateAndExecuteMergeStatement(
 		"flowName": destinationTableIdentifier,
 	}).Infof("[merge] merging records into %s...", destinationTableIdentifier)
 
-	result, err := normalizeRecordsTx.ExecContext(ctx, mergeStatement, destinationTableIdentifier)
+	// transaction for NormalizeRecords
+	mergeTx, err := c.database.BeginTx(c.ctx, nil)
+	if err != nil {
+		return 0, fmt.Errorf("unable to begin transactions for merge: %w", err)
+	}
+
+	// in case we return after error, ensure transaction is rolled back
+	defer func() {
+		deferErr := mergeTx.Rollback()
+		if deferErr != sql.ErrTxDone && deferErr != nil {
+			log.Errorf("unexpected error while rolling back transaction for merge: %v", deferErr)
+		}
+	}()
+
+	result, err := mergeTx.ExecContext(ctx, mergeStatement, destinationTableIdentifier)
 	if err != nil {
 		return 0, fmt.Errorf("failed to merge records into %s (statement: %s): %w",
 			destinationTableIdentifier, mergeStatement, err)
 	}
 
 	endTime := time.Now()
-	log.WithFields(log.Fields{
-		"flowName": destinationTableIdentifier,
-	}).Infof("[merge] merged records into %s, took: %d seconds",
+	log.Infof("[merge] merged records into %s, took: %d seconds",
 		destinationTableIdentifier, endTime.Sub(startTime)/time.Second)
 
 	return result.RowsAffected()