tree 543e69f03f759c9990587dd31f82b2f5b19b3159
parent 2f022a5ca0fc99670bcf197a1f89016cdf78d114
author Aleksandr Efimov <dzazheg@gmail.com> 1784303991 +0300
committer Impala Public Jenkins <impala-public-jenkins@cloudera.com> 1790952791 +0000

IMPALA-7996: Optimize constant-false outer joins

Constant FALSE or NULL ON conjuncts eliminate usable equi-join
predicates during expression rewriting. The classic planner then
chooses a nested-loop join although the join cannot produce a match.

Add a synthetic non-matching hash predicate for outer joins and drop
redundant remaining ON conjuncts. The predicate is what keeps this a
hash join: left where the analyzer put it, among the other conjuncts,
the FALSE leaves the planner choosing a nested loop join, and the
constant buys nothing. Replace the non-preserved input of
left and right outer joins with EmptySetNode.

Broadcast the empty build for constant-false left outer joins, even
with a SHUFFLE hint. Invert right outer joins so their empty input also
becomes the broadcast build. Keep full outer joins partitioned and use
random distribution on both inputs to avoid constant-key skew.

Add planner coverage for single-node and distributed plans with
literal, folded, and typed NULL predicates. Add query tests with
constant inline views to verify preserved-side row counts.

Change-Id: I6505825fc958720eec12e13d546661834f221b80
Assisted-by: gpt-5.6-sol (OpenAI Codex)
Reviewed-on: http://gerrit.cloudera.org:8080/24597
Reviewed-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>
Tested-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>