Re: postgresql meltdown on PlanetMath.org - Mailing list pgsql-performance

From Tom Lane
Subject Re: postgresql meltdown on PlanetMath.org
Date
Msg-id 495.1047882860@sss.pgh.pa.us
Whole thread Raw
In response to Re: postgresql meltdown on PlanetMath.org  ("Neil Conway" <neilc@samurai.com>)
Responses Re: postgresql meltdown on PlanetMath.org  (Logan Bowers <logan@datacurrent.com>)
List pgsql-performance
"Neil Conway" <neilc@samurai.com> writes:
> Sean Chittenden said:
> A "select count(*) FROM tblwordidx" initially took about 1 second to
> return a count of 2 million but after a few months it took several
> minutes of really hard HDD grinding.
>>
>> That's because there are dead entries in the index that weren't being
>> reused or cleaned up.  As I said, this has been fixed.

> That's doubtful: "select count(*) FROM foo" won't use an index.

To know what's going on, as opposed to guessing about it, we'd need to
know something about the physical sizes of the table and its indexes.
"vacuum verbose" output would be instructive...

But my best theorizing-in-advance-of-the-data guess is that Logan's
FSM settings are too small, causing free space to be leaked over time.
If a vacuum full restores the original performance then that's probably
the right answer.

            regards, tom lane

pgsql-performance by date:

Previous
From: Sean Chittenden
Date:
Subject: Re: postgresql meltdown on PlanetMath.org
Next
From: Greg Stark
Date:
Subject: Re: postgresql meltdown on PlanetMath.org