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David Kerr
Jun 22, 2012, 1:07:56 PM6/22/12
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I'm trying to work through a root cause on a performance problem. I'd like to
be able to "show" that a problem was fixed by analyzing the table.
what i've done is
set default_statistics_target=1
analyze <Table>
That gets rid of most of the rows in pg_stats, but i'm still getting decent performance.
It's possible that the existing stats were just not optimal, and i won't be able to get that back.
But I just want to verify that what i've done is the only real option that I have? am i missing anything
else that I could try?
(I'm on PG9.1)
Thanks.
Dave
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be able to "show" that a problem was fixed by analyzing the table.
what i've done is
set default_statistics_target=1
analyze <Table>
That gets rid of most of the rows in pg_stats, but i'm still getting decent performance.
It's possible that the existing stats were just not optimal, and i won't be able to get that back.
But I just want to verify that what i've done is the only real option that I have? am i missing anything
else that I could try?
(I'm on PG9.1)
Thanks.
Dave
--
Sent via pgsql-performance mailing list (pgsql-pe...@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-performance
Tom Lane
Jun 22, 2012, 1:27:51 PM6/22/12
to
David Kerr <d...@mr-paradox.net> writes:
> I'm trying to work through a root cause on a performance problem. I'd like to
> be able to "show" that a problem was fixed by analyzing the table.
> what i've done is
> set default_statistics_target=1
> analyze <Table>
> That gets rid of most of the rows in pg_stats, but i'm still getting decent performance.
I usually do something like
> I'm trying to work through a root cause on a performance problem. I'd like to
> be able to "show" that a problem was fixed by analyzing the table.
> what i've done is
> set default_statistics_target=1
> analyze <Table>
> That gets rid of most of the rows in pg_stats, but i'm still getting decent performance.
DELETE FROM pg_statistic WHERE starelid = 'foo'::regclass;
(you need to be superuser to be allowed to do this).
You may need to keep an eye on whether auto-analyze is coming along and
undoing what you did, too.
regards, tom lane
David Kerr
Jun 22, 2012, 2:04:36 PM6/22/12
to
On Fri, Jun 22, 2012 at 01:27:51PM -0400, Tom Lane wrote:
- David Kerr <d...@mr-paradox.net> writes:
- > I'm trying to work through a root cause on a performance problem. I'd like to
- > be able to "show" that a problem was fixed by analyzing the table.
-
- > what i've done is
- > set default_statistics_target=1
- > analyze <Table>
-
- > That gets rid of most of the rows in pg_stats, but i'm still getting decent performance.
-
- I usually do something like
-
- DELETE FROM pg_statistic WHERE starelid = 'foo'::regclass;
-
- (you need to be superuser to be allowed to do this).
-
- You may need to keep an eye on whether auto-analyze is coming along and
- undoing what you did, too.
-
- regards, tom lane
-
Awesome, thanks!
Dave
- David Kerr <d...@mr-paradox.net> writes:
- > I'm trying to work through a root cause on a performance problem. I'd like to
- > be able to "show" that a problem was fixed by analyzing the table.
-
- > what i've done is
- > set default_statistics_target=1
- > analyze <Table>
-
- > That gets rid of most of the rows in pg_stats, but i'm still getting decent performance.
-
- I usually do something like
-
- DELETE FROM pg_statistic WHERE starelid = 'foo'::regclass;
-
- (you need to be superuser to be allowed to do this).
-
- You may need to keep an eye on whether auto-analyze is coming along and
- undoing what you did, too.
-
- regards, tom lane
-
Awesome, thanks!
Dave
Bruce Momjian
Jul 3, 2012, 1:16:14 PM7/3/12
to
On Fri, Jun 22, 2012 at 11:04:36AM -0700, David Kerr wrote:
> On Fri, Jun 22, 2012 at 01:27:51PM -0400, Tom Lane wrote:
> - David Kerr <d...@mr-paradox.net> writes:
> - > I'm trying to work through a root cause on a performance problem. I'd like to
> - > be able to "show" that a problem was fixed by analyzing the table.
> -
> - > what i've done is
> - > set default_statistics_target=1
> - > analyze <Table>
> -
> - > That gets rid of most of the rows in pg_stats, but i'm still getting decent performance.
> -
> - I usually do something like
> -
> - DELETE FROM pg_statistic WHERE starelid = 'foo'::regclass;
> -
> - (you need to be superuser to be allowed to do this).
> -
> - You may need to keep an eye on whether auto-analyze is coming along and
> - undoing what you did, too.
> -
> - regards, tom lane
> -
>
> Awesome, thanks!
One cool trick I have seen is to do the DELETE pg_statistic in a multi-statement
> On Fri, Jun 22, 2012 at 01:27:51PM -0400, Tom Lane wrote:
> - David Kerr <d...@mr-paradox.net> writes:
> - > I'm trying to work through a root cause on a performance problem. I'd like to
> - > be able to "show" that a problem was fixed by analyzing the table.
> -
> - > what i've done is
> - > set default_statistics_target=1
> - > analyze <Table>
> -
> - > That gets rid of most of the rows in pg_stats, but i'm still getting decent performance.
> -
> - I usually do something like
> -
> - DELETE FROM pg_statistic WHERE starelid = 'foo'::regclass;
> -
> - (you need to be superuser to be allowed to do this).
> -
> - You may need to keep an eye on whether auto-analyze is coming along and
> - undoing what you did, too.
> -
> - regards, tom lane
> -
>
> Awesome, thanks!
transaction and then run query query, and roll it back. This allows the
statistics to be preserved, and for only your query to see empty
pg_statistic values for the table.
--
Bruce Momjian <br...@momjian.us> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ It's impossible for everything to be true. +
David Kerr
Jul 5, 2012, 1:53:57 AM7/5/12
to
Dave
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