pgsql: Unpin buffer before inplace update waits for an XID to end. - Mailing list pgsql-committers

Unpin buffer before inplace update waits for an XID to end.

Commit a07e03fd8fa7daf4d1356f7cb501ffe784ea6257 changed inplace updates
to wait for heap_update() commands like GRANT TABLE and GRANT DATABASE.
By keeping the pin during that wait, a sequence of autovacuum workers
and an uncommitted GRANT starved one foreground LockBufferForCleanup()
for six minutes, on buildfarm member sarus.  Prevent, at the cost of a
bit of complexity.  Back-patch to v12, like the earlier commit.  That
commit and heap_inplace_lock() have not yet appeared in any release.

Discussion: https://postgr.es/m/20241026184936.ae.nmisch@google.com

Branch
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REL_15_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/0fe002d0c9a5b04bb676e9cb8f80325f7129b5f3

Modified Files
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src/backend/access/heap/heapam.c | 10 +++++++---
src/backend/access/index/genam.c | 12 +++++-------
src/include/access/heapam.h      |  3 ++-
3 files changed, 14 insertions(+), 11 deletions(-)