Thread: pgsql: Set all_visible_according_to_vm correctly with DISABLE_PAGE_SKIP
pgsql: Set all_visible_according_to_vm correctly with DISABLE_PAGE_SKIP
From
Heikki Linnakangas
Date:
Set all_visible_according_to_vm correctly with DISABLE_PAGE_SKIPPING It's important for 'all_visible_according_to_vm' to correctly reflect whether the VM bit is set or not, even when we are not trusting the VM to skip pages, because contrary to what the comment said, lazy_scan_prune() relies on it. If it's incorrectly set to 'false', when the VM bit is in fact set, lazy_scan_prune() will try to set the VM bit again and dirty the page unnecessarily. As a result, if you used DISABLE_PAGE_SKIPPING, all heap pages were dirtied, even if there were no changes. We would also fail to clear any VM bits that were set incorrectly. This was broken in commit 980ae17310, so backpatch to v16. Backpatch-through: 16 Reviewed-by: Melanie Plageman, Peter Geoghegan Discussion: https://www.postgresql.org/message-id/3df2b582-dc1c-46b6-99b6-38eddd1b2784@iki.fi Branch ------ REL_16_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/407cb6c6589fa2b757c9f2724278ae101749d9f7 Modified Files -------------- src/backend/access/heap/vacuumlazy.c | 4 ---- 1 file changed, 4 deletions(-)