Thread: pgsql: Set the all-visible flag on heap page before writing WAL record,
pgsql: Set the all-visible flag on heap page before writing WAL record,
From
Heikki Linnakangas
Date:
Set the all-visible flag on heap page before writing WAL record, not after. If we set the all-visible flag after writing WAL record, and XLogInsert takes a full-page image of the page, the image would not include the flag. We will then proceed to set the VM bit, which would then be set without the corresponding all-visible flag on the heap page. Found by comparing page images on master and standby, after writing/replaying each WAL record. (There is still a discrepancy: the all-visible flag won't be set after replaying the HEAP_CLEAN record, even though it is set in the master. However, it will be set when replaying the HEAP2_VISIBLE record and setting the VM bit, so the all-visible flag and VM bit are always consistent on the standby, even though they are momentarily out-of-sync with master) Backpatch to 9.3 where this code was introduced. Branch ------ master Details ------- http://git.postgresql.org/pg/commitdiff/2a8e1ac598c864ac2775f33da21a117c363c6c7f Modified Files -------------- src/backend/commands/vacuumlazy.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-)