| From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
|---|---|
| To: | Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au> |
| Cc: | Oleg Bartunov <oleg(at)sai(dot)msu(dot)su>, Pgsql Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: fate of CLUSTER command ? |
| Date: | 2002-08-05 03:17:03 |
| Message-ID: | 200208050317.g753H3f02537@candle.pha.pa.us |
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| Lists: | pgsql-hackers |
Christopher Kings-Lynne wrote:
> > Clustering on one index doesn't decrease the performance of the other
> > indexes. Also, only >=7.3 will preserve all indexes during cluster.
>
> Sure it must? Since you are rearranging all on-disk rows to match a
> particular index (say user_id, username) then it will slow down other
> indexes (eg one just on username).
It will slow down other index scans only if there was some clustering on
those indexes before you ran the CLUSTER command.
--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 853-3000
+ If your life is a hard drive, | 830 Blythe Avenue
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