On 2014-09-29 16:35:12 -0400, Tom Lane wrote: > Andres Freund <and...@2ndquadrant.com> writes: > > On 2014-09-29 16:16:38 -0400, Tom Lane wrote: > >> I wonder why it's a fixed constant at all, and not something like > >> "wal_buffers / 8". > > > Because that'd be horrible performancewise on a system with many > > wal_buffers. There's several operations where all locks are checked in > > sequence (to see whether there's any stragglers that need to finish > > inserting) and even some where they're acquired concurrently (e.g. for > > xlog switch, checkpoint and such). > > Hm. Well, if there are countervailing considerations as to how large is a > good value, that makes it even less likely that it's sensible to expose > it as a user tunable.
Aren't there such considerations for most of the performance critical gucs? > A relevant analogy is that we don't expose a way > to adjust the number of lock table partitions at runtime. Which has worked out badly for e.g. the number of buffer partitions... Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers