refactor: optimize row handling in mssql extractor and transformer

internal/app/etl/extractors/consumer.go

@@ -68,7 +68,7 @@ func Consume(
 			wgActivePartitions.Done()
 
 			if rowsReadResult > 0 {
-				atomic.AddInt64(rowsRead, int64(rowsReadResult))
+				atomic.AddInt64(rowsRead, rowsReadResult)
 			}
 
 			if err != nil {
@@ -86,8 +86,6 @@ func Consume(
 					case chErrorsOut <- custom_errors.JobError{ShouldCancelJob: false, Msg: err.Error(), Prev: err}:
 					}
 				}
-
-				continue
 			}
 		}
 	}

internal/app/etl/extractors/mssql.go

@@ -89,14 +89,9 @@ func (mssqlEx *MssqlExtractor) Exec(
 	batchRows := make([]models.UnknownRowValues, 0, batchSize)
 	var rowsRead int64 = 0
 
-	rowValues := make([]any, len(columns))
-	scanArgs := make([]any, len(columns))
-	for i := range rowValues {
-		scanArgs[i] = &rowValues[i]
-	}
-
 	for rows.Next() {
-		if err := rows.Scan(scanArgs...); err != nil {
+		values, err := rows.Values()
+		if err != nil {
 			if len(batchRows) == 0 {
 				return rowsRead, err
 			}
@@ -110,7 +105,7 @@ func (mssqlEx *MssqlExtractor) Exec(
 		}
 		rowsRead++
 
-		batchRows = append(batchRows, rowValues)
+		batchRows = append(batchRows, values)
 		if len(batchRows) >= batchSize {
 			if err := flush(ctx, &partition, batchSize, batchRows, chBatchesOut); err != nil {
 				return rowsRead, err

internal/app/etl/transformers/mssql.go

@@ -74,6 +74,10 @@ func (mssqlTr *MssqlTransformer) ProcessBatch(
 			}
 		}
 
+		if rowValues == nil {
+			continue
+		}
+
 		for _, task := range transformationPlan {
 			val := rowValues[task.Index]
 			if val == nil {