From: | Jim Nasby <Jim(dot)Nasby(at)BlueTreble(dot)com> |
---|---|
To: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Bruce Momjian <bruce(at)momjian(dot)us> |
Cc: | Alexey Bashtanov <bashtanov(at)imap(dot)cc>, <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Autovacuum fails to keep visibility map up-to-date in mostly-insert-only-tables |
Date: | 2014-10-09 23:15:29 |
Message-ID: | 54371711.1060304@BlueTreble.com |
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Lists: | pgsql-hackers |
On 10/9/14, 4:03 PM, Alvaro Herrera wrote:
> Bruce Momjian wrote:
>
>> I agree this is a serious problem. We have discussed various options,
>> but have not decided on anything. The TODO list has:
>>
>> https://wiki.postgresql.org/wiki/Todo
>>
>> Improve setting of visibility map bits for read-only and insert-only
>> workloads
>>
>> http://www.postgresql.org/message-id/20130906001437.GA29264@momjian.us
>
> I hate to repeat myself, but I think autovacuum could be modified to run
> actions other than vacuum and analyze. In this specific case we could
> be running a table scan that checks only pages that don't have the
> all-visible bit set, and see if it can be set. (Of course, this idea
> needs refinement to avoid running over and over when the bit cannot be
> set on some pages for whatever reason.)
If we go down that road we should also think about having it proactively set hint bits...
--
Jim Nasby, Data Architect, Blue Treble Consulting
Data in Trouble? Get it in Treble! http://BlueTreble.com
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