Steve Carlin has uploaded this change for review. ( 
http://gerrit.cloudera.org:8080/22138


Change subject: IMPALA-13587: Calcite planner: Outer join not aggregating nulls 
properly
......................................................................

IMPALA-13587: Calcite planner: Outer join not aggregating nulls properly

The following query is producing incorrect results:

select t2.int_col y from alltypessmall t1 left outer join
alltypestiny t2 on t1.int_col = t2.int_col group by 1

... due to nulls not being aggregated properly on multiple nodes.
This is because the value equivalency graph is being set for the
join conjunct on an outer join. When a hash join partition node is
being used, there is an optimization that skips the aggregation step
that combines groups across nodes if, based on the value transfer
graph, it deduces that all data for the partition column is being
sent to the same node. 

The bug here is that even though an outer join is using an
equi-conjunct, the left and right side are different when data is not
found on the outer join side, where it becomse null.

The fix is to avoid registering the equi-conjunct if the values are
not always equal.

Change-Id: I57e9d4ad4c4af5a4c268e43ac2937064dab6ffd7
---
M 
java/calcite-planner/src/main/java/org/apache/impala/calcite/rel/node/ImpalaJoinRel.java
1 file changed, 6 insertions(+), 4 deletions(-)



  git pull ssh://gerrit.cloudera.org:29418/Impala-ASF refs/changes/38/22138/3
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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: newchange
Gerrit-Change-Id: I57e9d4ad4c4af5a4c268e43ac2937064dab6ffd7
Gerrit-Change-Number: 22138
Gerrit-PatchSet: 3
Gerrit-Owner: Steve Carlin <[email protected]>

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