Github user DaveBirdsall commented on a diff in the pull request:
https://github.com/apache/trafodion/pull/1543#discussion_r185329230
--- Diff: core/sql/optimizer/RelExpr.cpp ---
@@ -7880,11 +7880,17 @@ NABoolean
GroupByAgg::tryToPullUpPredicatesInPreCodeGen(
else
pulledPredicates += tempPulledPreds;
+ // just remove pulled up predicates from char. input
+ ValueIdSet newInputs(getGroupAttr()->getCharacteristicInputs());
+ myLocalExpr += selectionPred();
+ myLocalExpr -= tempPulledPreds;
+ myLocalExpr.weedOutUnreferenced(newInputs);
--- End diff --
Could you explain what is going on in this code? I notice that earlier in
the method we already added selectionPred() to myLocalExpr, and then removed
tempPulledPreds. I'm wondering why we are doing this again. Also, It's not
obvious to me why newInputs will have different values than myNewInputs, which
went through a similar calculation. An example might help.
---
