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pgsql: Fix incorrect non-strict join recheck in MERGE WHEN NOT MATCHED 2+ messages / 1 participants [nested] [flat]
* pgsql: Fix incorrect non-strict join recheck in MERGE WHEN NOT MATCHED @ 2024-10-03 11:54 Dean Rasheed <dean.a.rasheed@gmail.com> 0 siblings, 0 replies; 2+ messages in thread From: Dean Rasheed @ 2024-10-03 11:54 UTC (permalink / raw) To: pgsql-committers@lists.postgresql.org Fix incorrect non-strict join recheck in MERGE WHEN NOT MATCHED BY SOURCE. If a MERGE command contains WHEN NOT MATCHED BY SOURCE actions, the merge join condition is used by the executor to distinguish MATCHED from NOT MATCHED BY SOURCE cases. However, this qual is executed using the output from the join subplan node, which nulls the output from the source relation in the not matched case, and so the result may be incorrect if the join condition is "non-strict" -- for example, something like "src.col IS NOT DISTINCT FROM tgt.col". Fix this by enhancing the join recheck condition with an additional "src IS NOT NULL" check, so that it does the right thing when evaluated using the output from the join subplan. Noted by Tom Lane while investigating bug #18634 from Alexander Lakhin. Back-patch to v17, where WHEN NOT MATCHED BY SOURCE support was added to MERGE. Discussion: https://postgr.es/m/18634-db5299c937877f2b%40postgresql.org Branch ------ REL_17_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/d7d297f8449641bfd71750d04c302572a350052c Modified Files -------------- src/backend/optimizer/prep/prepjointree.c | 66 ++++++++++++++++++++++++++++--- src/test/regress/expected/merge.out | 22 +++++++++++ src/test/regress/sql/merge.sql | 18 +++++++++ 3 files changed, 101 insertions(+), 5 deletions(-) ^ permalink raw reply [nested|flat] 2+ messages in thread
* pgsql: Fix incorrect non-strict join recheck in MERGE WHEN NOT MATCHED @ 2024-10-03 11:54 Dean Rasheed <dean.a.rasheed@gmail.com> 0 siblings, 0 replies; 2+ messages in thread From: Dean Rasheed @ 2024-10-03 11:54 UTC (permalink / raw) To: pgsql-committers@lists.postgresql.org Fix incorrect non-strict join recheck in MERGE WHEN NOT MATCHED BY SOURCE. If a MERGE command contains WHEN NOT MATCHED BY SOURCE actions, the merge join condition is used by the executor to distinguish MATCHED from NOT MATCHED BY SOURCE cases. However, this qual is executed using the output from the join subplan node, which nulls the output from the source relation in the not matched case, and so the result may be incorrect if the join condition is "non-strict" -- for example, something like "src.col IS NOT DISTINCT FROM tgt.col". Fix this by enhancing the join recheck condition with an additional "src IS NOT NULL" check, so that it does the right thing when evaluated using the output from the join subplan. Noted by Tom Lane while investigating bug #18634 from Alexander Lakhin. Back-patch to v17, where WHEN NOT MATCHED BY SOURCE support was added to MERGE. Discussion: https://postgr.es/m/18634-db5299c937877f2b%40postgresql.org Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/dddb5640c6d32f3d48994dac0f4e80d0f4567262 Modified Files -------------- src/backend/optimizer/prep/prepjointree.c | 66 ++++++++++++++++++++++++++++--- src/test/regress/expected/merge.out | 22 +++++++++++ src/test/regress/sql/merge.sql | 18 +++++++++ 3 files changed, 101 insertions(+), 5 deletions(-) ^ permalink raw reply [nested|flat] 2+ messages in thread
end of thread, other threads:[~2024-10-03 11:54 UTC | newest] Thread overview: 2+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2024-10-03 11:54 pgsql: Fix incorrect non-strict join recheck in MERGE WHEN NOT MATCHED Dean Rasheed <dean.a.rasheed@gmail.com> 2024-10-03 11:54 pgsql: Fix incorrect non-strict join recheck in MERGE WHEN NOT MATCHED Dean Rasheed <dean.a.rasheed@gmail.com>
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