release-20.1: sql: fix planning of merge joins #52046
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`PlanToStreamColMap` was being incorrectly populated for the right side of the hash and merge joins in the case when there is at least one "internal" column coming from the left side that is not needed in the output (e.g. such columns might be needed during stream merges). This would result in propagating the wrong columns from the right side into the output of the join. I think this could only occur when planning merge joins because the hash joins have an empty merge ordering (I'm unsure about the case when the query has a sort on top of the hash join whether all columns from ORDER BY are included in the "output" columns of the join). Release note (bug fix): CockroachDB previously could crash on some queries with merge joins, and this has now been fixed.
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RaduBerinde
approved these changes
Jul 29, 2020
complete! 1 of 0 LGTMs obtained
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Backport 1/1 commits from #52042.
/cc @cockroachdb/release
sql: fix planning of merge joins
PlanToStreamColMapwas being incorrectly populated for the right sideof the hash and merge joins in the case when there is at least one
"internal" column coming from the left side that is not needed in the
output (e.g. such columns might be needed during stream merges). This
would result in propagating the wrong columns from the right side into
the output of the join. I think this could only occur when planning
merge joins because the hash joins have an empty merge ordering (I'm
unsure about the case when the query has a sort on top of the hash join
whether all columns from ORDER BY are included in the "output" columns
of the join).
Release note (bug fix): CockroachDB previously could crash on some
queries with merge joins, and this has now been fixed.