Re: Visibility map, partial vacuums - Mailing list pgsql-hackers

From Bruce Momjian
Subject Re: Visibility map, partial vacuums
Date
Msg-id 200901150131.n0F1VBa10679@momjian.us
Whole thread Raw
In response to Re: Visibility map, partial vacuums  (Andrew Dunstan <andrew@dunslane.net>)
List pgsql-hackers
Andrew Dunstan wrote:
> 
> 
> Bruce Momjian wrote:
> > Would someone tell me why 'autovacuum_freeze_max_age' defaults to 200M
> > when our wraparound limit is around 2B?
> >   
> 
> Presumably because of this (from the docs):
> 
> "The commit status uses two bits per transaction, so if 
> autovacuum_freeze_max_age has its maximum allowed value of a little less 
> than two billion, pg_clog can be expected to grow to about half a gigabyte."

Oh, that's interesting;  thanks.

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


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