On Tue, Feb 2, 2016 at 1:16 PM, Noah Misch <n...@leadboat.com> wrote: > On Tue, Feb 02, 2016 at 01:13:20AM +0100, Andres Freund wrote: >> is there any reason for the rather arbitrary and low checkpoint_timeout >> limit? > > Not that I know, and it is inconvenient. > >> I'm not sure what'd actually be a good upper limit. I'd be inclined to >> even go to as high as a week or so. A lot of our settings have >> upper/lower limits that aren't a good idea in general. > > In general, I favor having limits reflect fundamental system limitations > rather than paternalism. Therefore, I would allow INT_MAX (68 years).
+1. This way users can play as they wish. >> I'm also wondering if it'd not make sense to raise the default timeout >> to 15min or so. The upper ceiling for that really is recovery time, and >> that has really shrunk rather drastically due to faster cpus and >> architectural improvements in postgres (bgwriter, separate >> checkpointer/bgwriter, restartpoints, ...). > > Have those recovery improvements outpaced the increases in max recovery time > from higher core counts generating more WAL per minute? Perhaps having some numbers showing that the architecture improvements of Postgres really matter at constant checkpoint_segments for pgbench load would help to get into a better default value. I would tend to agree that as things speed up it would make sense to increase this value a bit though, even if Postgres is usually conservative enough in default parameters aimed at low-spec machines. -- Michael -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers