Re: opportunistic tuple freezing

I assume no progress has been made on testing the performance of this
patch.

---------------------------------------------------------------------------

Jeff Davis wrote:
> Attached is a patch to implement the idea discussed here:
>
> http://archives.postgresql.org/pgsql-hackers/2009-08/msg01137.php
>
> If VACUUM freezes one tuple on a page, it's likely that there are others
> on the same page that are close to vacuum_freeze_min_age, but not quite.
> Because the page is already dirty from freezing one tuple, it makes
> sense to be more aggressive about freezing the rest, in the hope that
> all the tuples will be frozen, and we will not have to dirty the page
> again later.
>
> This patch introduces a GUC vacuum_freeze_opportunistic_ratio. If one
> tuple on a page is frozen by vacuum, it effectively multiplies
> vacuum_freeze_min_age by vacuum_freeze_opportunistic_ratio and uses that
> lower (more aggressive) value only for the current page.
>
> The reason we don't just freeze all the tuples we can (effectively
> setting the vacuum_freeze_opportunistic_ratio to zero) is to preserve
> transaction ID information for diagnosing problems.
>
> Regards,
> Jeff Davis

[ Attachment, skipping... ]

>
> --
> Sent via pgsql-hackers mailing list (pgsql-hackers(at)postgresql(dot)org)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-hackers

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com
PG East: http://www.enterprisedb.com/community/nav-pg-east-2010.do
+ If your life is a hard drive, Christ can be your backup. +