| From: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
|---|---|
| To: | Josh Berkus <josh(at)agliodbs(dot)com> |
| Cc: | pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: multixacts woes |
| Date: | 2015-05-11 17:41:09 |
| Message-ID: | 20150511174109.GU2523@alvh.no-ip.org |
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| Lists: | pgsql-hackers |
Josh Berkus wrote:
> In terms of adding a new GUC in 9.5: can't we take a stab at auto-tuning
> this instead of adding a new GUC? We already have a bunch of freezing
> GUCs which fewer than 1% of our user base has any idea how to set.
If you have development resources to pour onto 9.5, I think it would be
better spent changing multixact usage tracking so that oldestOffset is
included in pg_control; also make pg_multixact truncation be WAL-logged.
With those changes, the need for a lot of pretty complicated code would
go away. The fact that truncation is done by both vacuum and checkpoint
causes a lot of the mess we were in (and from which Robert and Thomas
took us --- thanks guys!). Such a change is the first step towards
auto-tuning, I think.
--
Álvaro Herrera http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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