* Michael Paquier (michael.paqu...@gmail.com) wrote: > On Thu, Jan 19, 2017 at 5:01 AM, Peter Eisentraut > <peter.eisentr...@2ndquadrant.com> wrote: > > On 1/18/17 8:25 AM, Stephen Frost wrote: > >> I was actually thinking about it the other way- start out by changing > >> them to both be 5m and then document next to checkpoint_timeout (and > >> max_wal_size, perhaps...) that if you go changing those parameters (eg: > >> bumping up checkpoint_timeout to 30 minutes and max_wal_size up enough > >> that you're still checkpointing based on time and not due to running out > >> of WAL space) then you might need to consider raising the timeout for > >> pg_ctl to wait around for the server to finish going through crash > >> recovery due to all of the outstanding changes since the last > >> checkpoint. > > > > It is important for users to be aware of this, but I don't think the > > relationship between checkpoint_timeout and recovery time is linear, so > > it's unclear what the exact advice should be. > > This is a right assumption for steady workloads with few DDLs, but for > example once a couple of CREATE DATABASE records are in such a law is > broken.
I don't expect CREATE DATABASE to be terribly frequent, and it doesn't actually change the rule that the checkpoint_timeout is a maximum. Thanks! Stephen
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