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

From Andrew Dunstan
Subject Re: Visibility map, partial vacuums
Date
Msg-id 496E8EEA.8050206@dunslane.net
Whole thread Raw
In response to Re: Visibility map, partial vacuums  (Bruce Momjian <bruce@momjian.us>)
Responses Re: Visibility map, partial vacuums  (Bruce Momjian <bruce@momjian.us>)
List pgsql-hackers

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."

cheers

andrew



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