Re: vac truncation scan problems
| От | Jeff Janes |
|---|---|
| Тема | Re: vac truncation scan problems |
| Дата | |
| Msg-id | CAMkU=1xmTEiaY=5oMHsSQo5vd9V1Ze4kNLL0qN2eH0P_GXOaYw@mail.gmail.com обсуждение исходный текст |
| Ответ на | vac truncation scan problems (Jeff Janes <jeff.janes@gmail.com>) |
| Ответы |
Re: vac truncation scan problems
Re: vac truncation scan problems |
| Список | pgsql-hackers |
On Mon, Mar 30, 2015 at 8:54 PM, Jeff Janes <jeff.janes@gmail.com> wrote:
After freeing up the rows at the end of the table so it is eligible for truncation, then running a manual VACUUM to actually release the space, I kept running into the problem that the truncation scan was consistently suspended and then aborted due to a conflicting lock requested/held.But the perversity is that that conflicting lock request can only be coming, as far as I can tell, from the autovac process. I'm not sure how this happens, as I thought autovac never waited for locks but only obtained one if it were instantaneously available, but that it is the only explanation I can think of.I'm not seeing this in 9.4, but I'm not sure how deterministic it is so maybe that is just luck.
It looks like the culprit is this:
commit 0d831389749a3baaced7b984205b9894a82444b9
Author: Alvaro Herrera <alvherre@alvh.no-ip.org>
Date: Wed Mar 18 11:52:33 2015 -0300
Rationalize vacuuming options and parameters
I'd guess the autovac nature of the autovac process is getting lost in there where, but I don't see where.
Cheers,
Jeff
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