Use target table columns for INSERT into existing table only

Author: marsaly79

ydb/library/yql/providers/yt/provider/yql_yt_datasink_type_ann.cpp

@@ -460,8 +460,11 @@ class TYtDataSinkTypeAnnotationTransformer : public TVisitorTransformerBase {
             if (NCommon::NeedToRenamePgSelectColumns(pgSelect)) {
                 TExprNode::TPtr output;
 
-                Y_ENSURE(outTableInfo.RowSpec);
-                bool result = NCommon::RenamePgSelectColumns(pgSelect, output, outTableInfo.RowSpec->GetColumnOrder(), ctx, *State_->Types);
+                const auto& columnOrder = (outTableInfo.RowSpec)
+                    ? outTableInfo.RowSpec->GetColumnOrder()
+                    : contentColumnOrder;
+
+                bool result = NCommon::RenamePgSelectColumns(pgSelect, output, columnOrder, ctx, *State_->Types);
                 if (!result) {
                     return TStatus::Error;
                 }