Cherry-pick two upstream fixes for minor release regressions (v16)#895
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hlinnaka merged 2 commits intoREL_16_STABLE_neonfrom Feb 17, 2026
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Commit 1e7fe06c10c0a8da9dd6261a6be8d405dc17c728 changed pg_mbstrlen_with_len() to ereport(ERROR) if the input ends in an incomplete character. Most callers want that. text_substring() does not. It detoasts the most bytes it could possibly need to get the requested number of characters. For example, to extract up to 2 chars from UTF8, it needs to detoast 8 bytes. In a string of 3-byte UTF8 chars, 8 bytes spans 2 complete chars and 1 partial char. Fix this by replacing this pg_mbstrlen_with_len() call with a string traversal that differs by stopping upon finding as many chars as the substring could need. This also makes SUBSTRING() stop raising an encoding error if the incomplete char is past the end of the substring. This is consistent with the general philosophy of the above commit, which was to raise errors on a just-in-time basis. Before the above commit, SUBSTRING() never raised an encoding error. SUBSTRING() has long been detoasting enough for one more char than needed, because it did not distinguish exclusive and inclusive end position. For avoidance of doubt, stop detoasting extra. Back-patch to v14, like the above commit. For applications using SUBSTRING() on non-ASCII column values, consider applying this to your copy of any of the February 12, 2026 releases. Reported-by: SATŌ Kentarō <ranvis@gmail.com> Reviewed-by: Thomas Munro <thomas.munro@gmail.com> Bug: #19406 Discussion: https://postgr.es/m/19406-9867fddddd724fca@postgresql.org Backpatch-through: 14
'latest_page_number' is set to the correct value, according to
nextOffset, early at system startup. Contrary to the comment, it hence
should be set up correctly by the time we get to WAL replay.
This fixes a failure to replay WAL generated on older minor versions,
before commit 789d65364c (18.2, 17.8, 16.12, 15.16, 14.21). The
failure occurs after a truncation record has been replayed and looks
like this:
FATAL: could not access status of transaction 858112
DETAIL: Could not read from file "pg_multixact/offsets/000D" at offset 24576: read too few bytes.
CONTEXT: WAL redo at 3/2A3AB408 for MultiXact/CREATE_ID: 858111 offset 6695072 nmembers 5: 1048228 (sh) 1048271 (keysh) 1048316 (sh) 1048344 (keysh) 1048370 (sh)
Reported-by: Sebastian Webber <sebastian@swebber.me>
Reviewed-by: Andrey Borodin <x4mmm@yandex-team.ru>
Reviewed-by: Kirill Reshke <reshkekirill@gmail.com>
Discussion: https://www.postgresql.org/message-id/20260214090150.GC2297@p46.dedyn.io;lightning.p46.dedyn.io
Backpatch-through: 14-18
sdebnath
approved these changes
Feb 16, 2026
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