Re: [COMMITTERS] pgsql: Add pages deleted from pending list to FSM

Поиск
Список
Период
Сортировка
От Jeff Janes
Тема Re: [COMMITTERS] pgsql: Add pages deleted from pending list to FSM
Дата
Msg-id CAMkU=1xZ7J2tGin25CBDA+Agk_LEXXJyx0FrtESEN+SBAs8Hyg@mail.gmail.com
обсуждение исходный текст
Ответ на Re: [COMMITTERS] pgsql: Add pages deleted from pending list to FSM  (Tom Lane <tgl@sss.pgh.pa.us>)
Ответы Re: [COMMITTERS] pgsql: Add pages deleted from pending list to FSM  (Fujii Masao <masao.fujii@gmail.com>)
Список pgsql-hackers
Дерево обсуждения
On Fri, Sep 18, 2015 at 6:27 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
[ moving thread to -hackers ]

Fujii Masao <masao.fujii@gmail.com> writes:
> So autoanalyze still doesn't call IndexFreeSpaceMapVacuum().
> That is, only backend can clean the list in INSERT-only workload.
> I don't think that this is desirable. Because the backend will
> periodically take a big performance penalty.

Calling IndexFreeSpaceMapVacuum is only need to reuse the space freed up by cleaning the pending list.

The list is still getting cleaned and truncated by autoanalyze, it is just that the space is not getting marked for reuse.

When I wrote this, my thought was that a table vacuum is going to call IndexFreeSpaceMapVacuum() from another place in its code and so should not call it here as well.  I neglected to consider the autoanalyze case.

 
> So I'm thinking that even autoanalyze should call IndexFreeSpaceMapVacuum()
> to clean the list in a background, in order to avoid such spikes in
> INSERT response time. Thought?

But it already is cleaning the list.  If that space is not marked as reusable, that causes index bloat, but doesn't cause latency spikes.



It seems quite bizarre for auto-analyze to do that.  auto-vacuum, sure,
but I do not think this should get plugged into ANALYZE.

It may be odd that autoanalyze cleans the list at all (which this patch doesn't change), but given that it does clean the list I don't see why it would be bizarre to make the cleaned-up space re-usable.

Cheers,

Jeff

В списке pgsql-hackers по дате отправления:

Предыдущее
От: "Daniel Verite"
Дата:
Сообщение: Re: [patch] Proposal for \rotate in psql
Следующее
От: Vladimir Borodin
Дата:
Сообщение: Re: RFC: replace pg_stat_activity.waiting with something more descriptive