Re: Visibility map, partial vacuums

Gregory Stark wrote:
> Bruce Momjian <bruce@momjian.us> writes:
> 
> > Would someone tell me why 'autovacuum_freeze_max_age' defaults to 200M
> > when our wraparound limit is around 2B?
> 
> I suggested raising it dramatically in the post you quote and Heikki pointed
> it controls the maximum amount of space the clog will take. Raising it to,
> say, 800M will mean up to 200MB of space which might be kind of annoying for a
> small database.
> 
> It would be nice if we could ensure the clog got trimmed frequently enough on
> small databases that we could raise the max_age. It's really annoying to see
> all these vacuums running 10x more often than necessary.

I always assumed that it was our 4-byte xid that was requiring our
vacuum freeze, but I now see our limiting factor is the size of clog;
interesting.

--  Bruce Momjian  <bruce@momjian.us>        http://momjian.us EnterpriseDB
http://enterprisedb.com
 + If your life is a hard drive, Christ can be your backup. +