Re: slow query execution
| От | Andrew Sullivan |
|---|---|
| Тема | Re: slow query execution |
| Дата | |
| Msg-id | 20070530164553.GK16260@phlogiston.dyndns.org обсуждение исходный текст |
| Ответ на | slow query execution (Trigve Siver <trigves@yahoo.com>) |
| Список | pgsql-sql |
On Wed, May 30, 2007 at 08:56:45AM -0700, Trigve Siver wrote: > Hi all, > > This query executes very slow: > > select (select count(*) from customer where id <= a.id) as row, id, > from customer as a order by id; So you are trying to get the ordinal position of every ID in the table? I'm not surprised it takes a long time -- you have to join the whole table to itself and then do a lot of counting. Are you just trying to get the "row number" for your query answer? You can do this with a temporary sequence, among other approaches, more cheaply. A -- Andrew Sullivan | ajs@crankycanuck.ca Users never remark, "Wow, this software may be buggy and hard to use, but at least there is a lot of code underneath." --Damien Katz
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