Github user zellerh commented on a diff in the pull request:
https://github.com/apache/trafodion/pull/1581#discussion_r196474928
--- Diff: core/sql/optimizer/RelExpr.cpp ---
@@ -13341,6 +13341,36 @@ void GenericUpdate::pushdownCoveredExpr(const
ValueIdSet &outputExpr,
newExternalInputs,
predicatesOnParent,
&localExprs);
+
+ if (avoidHalloween() && child(0) &&
+ child(0)->getOperatorType() == REL_SCAN &&
+ child(0)->getGroupAttr())
+ {
+ ValueIdSet cur_output =
child(0)->getGroupAttr()->getCharacteristicOutputs();
--- End diff --
This works, but is is not very efficient to create a copy of a ValueIdSet
just to check whether it is empty. You could just check
```
if (child(0)->getGroupAttr()->getCharacteristicOutputs().isEmpty())
```
in the line below.
---
