Re: Use of max_slot_wal_keep_size parameter

Don Seiler <don(at)seiler(dot)us> writes:
> On Tue, Mar 26, 2024 at 9:09 AM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> ... 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.

Can you measure your WAL emission rate? What you want I think is some
small multiple of the max amount of WAL emitted between checkpoints.

regards, tom lane