| From: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
|---|---|
| To: | 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 21:03:00 |
| Message-ID: | 20141009210300.GI7043@eldon.alvh.no-ip.org |
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| Thread: | |
| Lists: | pgsql-hackers |
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.)
--
Álvaro Herrera http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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