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

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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 becomes null.

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

Change-Id: I57e9d4ad4c4af5a4c268e43ac2937064dab6ffd7
Reviewed-on: http://gerrit.cloudera.org:8080/22138
Reviewed-by: Michael Smith <michael.smith@cloudera.com>
Reviewed-by: Riza Suminto <riza.suminto@cloudera.com>
Tested-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>
Reviewed-by: Steve Carlin <scarlin@cloudera.com>
This commit is contained in:
Steve Carlin
2024-11-27 12:50:49 -08:00
parent b449381cc8
commit 5b4427ed1b
1 changed files with 6 additions and 4 deletions
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10
java/calcite-planner/src/main/java/org/apache/impala/calcite/rel/node/ImpalaJoinRel.java
View File

@@ -143,13 +143,15 @@ public class ImpalaJoinRel extends Join
rightInput.planNode_, false /* not a straight join */, distMode, joinOp,
equiJoinConjuncts, otherJoinConjuncts, filterConjuncts, analyzer);
if (equiJoinConjuncts.size() > 0) {
// register the equi and non-equi join conjuncts with the analyzer such that
// value transfer graph creation can consume it
// register the equi join conjuncts with the analyzer such that
// value transfer graph creation can consume it. It is only useful
// in the value transfer graph if the value transfer is equal on
// both sides. Any outer join is removed since the value on the outer
// join side could be NULL when the left side is not NULL.
if (equiJoinConjuncts.size() > 0 && joinOp == JoinOperator.INNER_JOIN) {
List<Expr> equiJoinExprs = new ArrayList<Expr>(equiJoinConjuncts);
analyzer.registerConjuncts(getJoinConjunctListToRegister(equiJoinExprs));
}
analyzer.registerConjuncts(getJoinConjunctListToRegister(otherJoinConjuncts));
return new NodeWithExprs(joinNode, outputExprs);
}