Thread: Clustering system catalog indexes
Is it worth us marking any system catalog indexes as clusterable by default for performance? Chris
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@candle.pha.pa.us | (610) 359-1001+ If your life is a hard drive, | 13 Roberts Road + Christ can be your backup. | Newtown Square, Pennsylvania19073
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)
> 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
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@candle.pha.pa.us | (610) 359-1001+ If your life is a hard drive, | 13 Roberts Road + Christ can be your backup. | Newtown Square, Pennsylvania19073
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@candle.pha.pa.us | (610)
359-1001+ If your life is a hard drive, | 13 Roberts Road + Christ can be your backup. | Newtown Square,
Pennsylvania19073