| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Jim Nasby <Jim(dot)Nasby(at)bluetreble(dot)com> |
| Cc: | Bruce Momjian <bruce(at)momjian(dot)us>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Greg Stark <stark(at)mit(dot)edu>, Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, Simon Riggs <simon(dot)riggs(at)2ndquadrant(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, Pavan Deolasee <pavan(dot)deolasee(at)gmail(dot)com>, Simon Riggs <simon(at)2ndquadrant(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Michael Paquier <michael(dot)paquier(at)gmail(dot)com>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Peter Eisentraut <peter_e(at)gmx(dot)net> |
| Subject: | Re: Turning off HOT/Cleanup sometimes |
| Date: | 2015-04-23 19:40:36 |
| Message-ID: | CA+TgmoboUWDDDzYCkGB_DpRN1Z5q1YkaiCFHQouho5qCKSvHKw@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Thu, Apr 23, 2015 at 10:44 AM, Jim Nasby <Jim(dot)Nasby(at)bluetreble(dot)com> wrote:
> On 4/23/15 8:25 AM, Robert Haas wrote:
>> Some users are partitioning tables just so that each
>> partition can be autovac'd separately. That really shouldn't be
>> required.
>
> Are they doing this for improved heap scan performance? Index scan
> performance? If the table wasn't partitioned, would they need more than one
> pass through the indexes due to exhausting maintenance_work_mem?
I don't know of anyone with a properly-configured system who needs
more than one pass through the indexes due to exhausting
maintenance_work_mem. The issue is that you have to vacuum a table
frequently enough to avoid accumulating bloat. The frequency with
which you need to vacuum varies depending on the size of the table and
how frequently it's updated. However, a large, heavily-updated table
can take long enough to vacuum that, by the time you get done, it's
already overdue to be vacuumed again. That's a problem.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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