On Tue, Sep 20, 2016 at 4:09 PM, Andres Freund <and...@anarazel.de> wrote: > On 2016-09-20 16:05:44 -0400, Robert Haas wrote: >> On Tue, Sep 20, 2016 at 2:49 PM, Peter Eisentraut >> <peter.eisentr...@2ndquadrant.com> wrote: >> > On 8/24/16 9:31 PM, Robert Haas wrote: >> >> I'd like to propose that we increase the default WAL segment size, >> >> which is currently 16MB. >> > >> > While the discussion about the best default value is ongoing, maybe we >> > should at least *allow* some larger sizes, for testing out. Currently, >> > configure says "Allowed values are 1,2,4,8,16,32,64.". What might be a >> > good new upper limit? > > I'm doubtful it's worth increasing this. > >> 1GB? > > That sounds way too big to me. WAL file allocation would trigger pretty > massive IO storms during zeroing, max_wal_size is going to be hard to > tune, the amounts of dirty data during bulk loads is going to be very > hard to control. If somebody wants to do something like this they > better be well informed enough to override a #define.
EnterpriseDB has customers generating multiple TB of WAL per day. Even with a 1GB segment size, some of them will fill multiple files per minute. At the current limit of 64MB, a few of them would still fill more than one file per second. That is not sane. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers