From: Peter Geoghegan <pg@bowt.ie>
To: pgsql-committers@lists.postgresql.org
Subject: pgsql: Make NULL tuple values always advance skip arrays.
Date: Mon, 28 Apr 2025 16:11:45 +0000
Message-ID: <E1u9R57-000250-27@gemulon.postgresql.org> (raw)
Make NULL tuple values always advance skip arrays.
_bt_check_compare neglected to handle a case that can arise when the
scan's keys are temporarily treated as nonrequired, as an optimization:
whenever a NULL tuple value was encountered that had a skip array whose
current element wasn't already NULL, _bt_check_compare failed to advance
the array to the NULL element. This allowed _bt_check_compare to fail
to return matching tuples containing a NULL value (though only with an
array column that came before a skip array column with NULLs, and only
during _bt_readpage calls that set pstate.forcenonrequired=true on a
page where the higher-order column also had to advance).
To fix, teach _bt_check_compare to handle this case just like any other
case where a skip array key is unsatisfied and must be advanced directly
(due to the key being considered a nonrequired key).
Oversight in commit 8a510275, which optimized nbtree search scan key
comparisons with skip arrays.
Author: Peter Geoghegan <pg@bowt.ie>
Reported-By: Mark Dilger <mark.dilger@enterprisedb.com>
Discussion: https://postgr.es/m/CAHgHdKtLFWZcjr87hMH0hYDHgcifu4Tj7iHz-xh8qsJREt5cqA@mail.gmail.com
Branch
------
master
Details
-------
https://git.postgresql.org/pg/commitdiff/b75fedcab7916e1c955dbab565b7ad0cee6b37c6
Modified Files
--------------
src/backend/access/nbtree/nbtutils.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
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To: pgsql-committers@postgresql.org
Cc: pg@bowt.ie, pgsql-committers@lists.postgresql.org
Subject: Re: pgsql: Make NULL tuple values always advance skip arrays.
In-Reply-To: <E1u9R57-000250-27@gemulon.postgresql.org>
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