Github user zellerh commented on a diff in the pull request:
https://github.com/apache/incubator-trafodion/pull/1253#discussion_r142546324
--- Diff: core/sql/generator/GenRelUpdate.cpp ---
@@ -292,8 +292,85 @@ static short genUpdExpr(
return 0;
}
-static short genUpdConstraintExpr(Generator *generator)
+// Used to generate update or insert constraint expressions for update
operators
+static short genUpdConstraintExpr(Generator * generator,
+ ItemExpr * constrTree,
+ const ValueIdSet & constraintColumns,
+ ValueIdArray & targetRecExprArray,
+ ex_expr ** targetExpr /* out */)
{
+ ExpGenerator * expGen = generator->getExpGenerator();
+
+ // The Attributes for the table columns refer to the old values of the
column.
+ // The constraints must operate on the new values, though. So we must do
a
+ // switcheroo on the Attributes for the update expression. The target
value IDs
+ // come from targetRecExprArray.
+
+ ValueIdList savedSourceVIDlist;
+ NAList<Attributes*> savedSourceAttrsList(generator->wHeap());
+
+ for (ValueId sourceValId = constraintColumns.init();
+ constraintColumns.next(sourceValId);
+ constraintColumns.advance(sourceValId))
+ {
+ NAColumn * sourceCol =
((IndexColumn*)sourceValId.getItemExpr())->getNAColumn();
+ ValueId targetValId;
+ NABoolean found = FALSE;
+ for (CollIndex ni = 0; (!found) && (ni <
targetRecExprArray.entries()); ni++)
+ {
+ const ItemExpr *assignExpr =
targetRecExprArray[ni].getItemExpr();
+ targetValId =
assignExpr->child(0)->castToItemExpr()->getValueId();
+ NAColumn *targetCol = NULL;
+ if (targetValId.getItemExpr()->getOperatorType() ==
ITM_BASECOLUMN)
+ targetCol =
((BaseColumn*)targetValId.getItemExpr())->getNAColumn();
+ else if (targetValId.getItemExpr()->getOperatorType() ==
ITM_INDEXCOLUMN)
+ targetCol =
((IndexColumn*)targetValId.getItemExpr())->getNAColumn();
+
+ if ((targetCol) &&
--- End diff --
Yes, sorry to comment on surround code. If both source and target share the
same NATable, then wouldn't the following be sufficient:
```c++
if ((targetCol) && courceCol == targetCol)
...
```
Another option would be to compare their column number:
```c++
CMPASSERT(sourceCol->getNATable() == targetCol->getNATable());
if (targetCol && sourceCol->getPosition() == targetCol->getPosition())
...
```
One thing might be a problem: I wonder whether in some cases we might
suppress caching of the NATable on the insert side and allow it on the select
side or vice versa.
I wonder whether @sureshsubbiah has any additional comments on this topic.
---
