Fix handling of NULLs when merging BRIN summaries
When merging BRIN summaries, union_tuples() did not correctly update the
target hasnulls/allnulls flags. When merging all-NULL summary into a
summary without any NULL values, the result had both flags set to false
(instead of having hasnulls=true).
This happened because the code only considered the hasnulls flags,
ignoring the possibility the source summary has allnulls=true.
Discovered while investigating issues with handling empty BRIN ranges
and handling of NULL values, but it's a separate problem (has nothing to
do with empty ranges).
Fixed by considering both flags on the source summary, and updating the
hasnulls flag on the target summary.
Backpatch to 11. The bug exists since 9.5 (where BRIN indexes were
introduced), but those releases are EOL already.
Discussion: https://postgr.es/m/9d993d0d-e431-2196-9ccc-0554d0e60154%40enterprisedb.com
Branch
------
REL_14_STABLE
Details
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https://git.postgresql.org/pg/commitdiff/3f1356e5d60a310b9ceb73497ec49af1b69bafa8
Modified Files
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src/backend/access/brin/brin.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
