| From: | "Jonah H(dot) Harris" <jonah(dot)harris(at)gmail(dot)com> |
|---|---|
| To: | "Kenneth Marshall" <ktm(at)rice(dot)edu> |
| Cc: | "Jessica Richard" <rjessil(at)yahoo(dot)com>, pgsql-admin(at)postgresql(dot)org |
| Subject: | Re: select count(*) from a large table is very slow |
| Date: | 2007-05-18 13:30:36 |
| Message-ID: | 36e682920705180630y2c28cdc5m14af94d6d62e1daf@mail.gmail.com |
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| Lists: | pgsql-admin |
On 5/18/07, Kenneth Marshall <ktm(at)rice(dot)edu> wrote:
> Make a summary table and select from there instead.
Yes, a summary table updated by triggers is the only way to have
correct numbers... but you also pay the overhead of maintaining those
numbers on every INSERT/UPDATE statement. If you just need
*reasonable* guesstimates, use reltuples in pg_class after an analyze.
--
Jonah H. Harris, Software Architect | phone: 732.331.1324
EnterpriseDB Corporation | fax: 732.331.1301
33 Wood Ave S, 3rd Floor | jharris(at)enterprisedb(dot)com
Iselin, New Jersey 08830 | http://www.enterprisedb.com/
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