Re: Feedback on getting rid of VACUUM FULL
От | Simon Riggs |
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Тема | Re: Feedback on getting rid of VACUUM FULL |
Дата | |
Msg-id | 1253173645.9666.130.camel@ebony.2ndQuadrant обсуждение исходный текст |
Ответ на | Re: Feedback on getting rid of VACUUM FULL (Tom Lane <tgl@sss.pgh.pa.us>) |
Список | pgsql-hackers |
On Wed, 2009-09-16 at 23:12 -0400, Tom Lane wrote: > Jeff Davis <pgsql@j-davis.com> writes: > > On Wed, 2009-09-16 at 21:48 -0400, Tom Lane wrote: > >> Yeah, I was just wondering about that myself. Seems like there would > >> be lots of situations where short exclusive-lock intervals could be > >> tolerated, even though not long ones. > > > But a short-lived exclusive lock can turn into a long-lived exclusive > > lock if there are long-lived transactions ahead of it in the queue. We > > probably don't want to automate anything by default that acquires > > exclusive locks, even for a short time. However, I agree that it's fine > > in many situations if the administrator is choosing it. > > Right, which is why autovacuum can't have anything to do with this. We already do this and we already solved the problem associated with it. VACUUM tries to grab a conditional lock to shrink the table. We can do the same thing here, just retry the lock for each chunk cleaned. -- Simon Riggs www.2ndQuadrant.com
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