Re: Setting vacuum_freeze_min_age really low - Mailing list pgsql-performance

From Robert Haas
Subject Re: Setting vacuum_freeze_min_age really low
Date
Msg-id CA+TgmobGz+PUrG4KqZ1wt84+Q1RvCbDUi-gL_AbF0VYWPtUFDg@mail.gmail.com
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In response to Re: Setting vacuum_freeze_min_age really low  (Andres Freund <andres@2ndquadrant.com>)
Responses Re: Setting vacuum_freeze_min_age really low
List pgsql-performance
On Sun, May 12, 2013 at 8:50 AM, Andres Freund <andres@2ndquadrant.com> wrote:
> [ a response that I entirely agree with ]

+1 to all that.

It's maybe worth noting that it's probably fairly uncommon for vacuum
to read a page and not dirty it, because if the page is all-visible,
we won't read it.  And if it's not all-visible, and there's nothing
else interesting to do with it, we'll probably make it all-visible,
which will dirty it.  It can happen, if for example we vacuum a page
with no dead tuples while the inserting transaction is still running,
or committed but not yet all-visible.  Of course, in those cases we
won't be able to freeze, either.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company


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