| Lists: | pgsql-hackers |
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| From: | Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au> |
|---|---|
| To: | Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Clustering system catalog indexes |
| Date: | 2004-04-28 06:04:34 |
| Message-ID: | 408F4972.6050802@familyhealth.com.au |
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| Lists: | pgsql-hackers |
Is it worth us marking any system catalog indexes as clusterable by
default for performance?
Chris
| From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
|---|---|
| To: | Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au> |
| Cc: | Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Clustering system catalog indexes |
| Date: | 2004-05-20 01:43:22 |
| Message-ID: | 200405200143.i4K1hMe09781@candle.pha.pa.us |
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Christopher Kings-Lynne wrote:
> Is it worth us marking any system catalog indexes as clusterable by
> default for performance?
Not sure. Most of the system stuff is loaded in a pretty good order, and
cluster is only good if you are going after seveal rows of identical
value or similar value in the same table, and I can't think of a case
where this would help. Can others? It is a good question.
--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073
| From: | Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl> |
|---|---|
| To: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
| Cc: | Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au>, Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Clustering system catalog indexes |
| Date: | 2004-05-20 02:02:17 |
| Message-ID: | 20040520020217.GA13544@dcc.uchile.cl |
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On Wed, May 19, 2004 at 09:43:22PM -0400, Bruce Momjian wrote:
> Christopher Kings-Lynne wrote:
> > Is it worth us marking any system catalog indexes as clusterable by
> > default for performance?
>
> Not sure. Most of the system stuff is loaded in a pretty good order, and
> cluster is only good if you are going after seveal rows of identical
> value or similar value in the same table, and I can't think of a case
> where this would help. Can others? It is a good question.
pg_attribute maybe?
--
Alvaro Herrera (<alvherre[a]dcc.uchile.cl>)
"Cómo ponemos nuestros dedos en la arcilla del otro. Eso es la amistad; jugar
al alfarero y ver qué formas se pueden sacar del otro" (C. Halloway en
La Feria de las Tinieblas, R. Bradbury)
| From: | Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au> |
|---|---|
| To: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
| Cc: | Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Clustering system catalog indexes |
| Date: | 2004-05-20 02:09:53 |
| Message-ID: | 40AC1371.1010609@familyhealth.com.au |
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| Lists: | pgsql-hackers |
> Not sure. Most of the system stuff is loaded in a pretty good order, and
> cluster is only good if you are going after seveal rows of identical
> value or similar value in the same table, and I can't think of a case
> where this would help. Can others? It is a good question.
pg_attribute would commonly be fetched via the attrelid. However, I
guess it's all cached anyway...
Chris
| From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
|---|---|
| To: | Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl> |
| Cc: | Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au>, Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Clustering system catalog indexes |
| Date: | 2004-05-20 02:58:32 |
| Message-ID: | 200405200258.i4K2wWD20880@candle.pha.pa.us |
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| Lists: | pgsql-hackers |
Alvaro Herrera wrote:
> On Wed, May 19, 2004 at 09:43:22PM -0400, Bruce Momjian wrote:
> > Christopher Kings-Lynne wrote:
> > > Is it worth us marking any system catalog indexes as clusterable by
> > > default for performance?
> >
> > Not sure. Most of the system stuff is loaded in a pretty good order, and
> > cluster is only good if you are going after seveal rows of identical
> > value or similar value in the same table, and I can't think of a case
> > where this would help. Can others? It is a good question.
>
> pg_attribute maybe?
Ah, good point. Because of vacuum reuse, it could grab rows in
different locations when creating a table. Good point.
Added to TODO:
o Add default clustering to system tables
--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073
| From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
|---|---|
| To: | Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au> |
| Cc: | Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Clustering system catalog indexes |
| Date: | 2004-05-20 02:58:51 |
| Message-ID: | 200405200258.i4K2wpd20987@candle.pha.pa.us |
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| Lists: | pgsql-hackers |
Christopher Kings-Lynne wrote:
> > Not sure. Most of the system stuff is loaded in a pretty good order, and
> > cluster is only good if you are going after seveal rows of identical
> > value or similar value in the same table, and I can't think of a case
> > where this would help. Can others? It is a good question.
>
> pg_attribute would commonly be fetched via the attrelid. However, I
> guess it's all cached anyway...
Yes, but that cache has to be loaded sometime.
--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073