On Tue, Mar 26, 2024 at 9:09 AM Tom Lane <tgl@xxxxxxxxxxxxx> wrote:
My immediate reaction is that 3% is a mighty small margin for error.
I don't know exactly how max_slot_wal_keep_size is enforced these
days, but in the past restrictions like that were implemented by
deciding during a checkpoint whether to unlink a no-longer-needed WAL
file (if we had too much WAL) or rename/recycle it to become a future
WAL segment (if not). So you could overshoot the specified target by
more or less the amount of WAL that could be emitted between two
checkpoints. Perhaps it's tighter nowadays, but I really doubt that
it's exact-to-the-kilobyte-at-all-times.
In this case, the total volume size was 60GB and we had the parameter set to 58GB but I imagine that can still be overwhelmed quickly. Maybe we should target a 20% buffer zone? We have wal_keep_size defaulted at 0.
Thanks,
Don.
--
Don Seiler
www.seiler.us
www.seiler.us
