On 01/03/2015 12:56 AM, Heikki Linnakangas wrote: > On 01/03/2015 12:28 AM, Josh Berkus wrote: >> On 01/02/2015 01:57 AM, Heikki Linnakangas wrote: >>> wal_keep_segments does not affect the calculation of CheckPointSegments. >>> If you set wal_keep_segments high enough, checkpoint_wal_size will be >>> exceeded. The other alternative would be to force a checkpoint earlier, >>> i.e. lower CheckPointSegments, so that checkpoint_wal_size would be >>> honored. However, if you set wal_keep_segments high enough, higher than >>> checkpoint_wal_size, it's impossible to honor checkpoint_wal_size no >>> matter how frequently you checkpoint. >> >> So you're saying that wal_keep_segments is part of the max_wal_size >> total, NOT in addition to it? > > Not sure what you mean. wal_keep_segments is an extra control that can > prevent WAL segments from being recycled. It has the same effect as > archive_command failing for N most recent segments, if that helps.
I mean, if I have these settings: max_wal_size* = 256MB wal_keep_segments = 8 ... then my max wal size is *still* 256MB, NOT 384MB? If that's the case (and I think it's a good plan), then as a follow-on, we should prevent users from setting wal_keep_segments to more than 50% of max_wal_size, no? (* max_wal_size == checkpoint_wal_size, per prior email) -- Josh Berkus PostgreSQL Experts Inc. http://pgexperts.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers