Re: count(*) optimization
От | Nikola Ivacic |
---|---|
Тема | Re: count(*) optimization |
Дата | |
Msg-id | 02b301c2b731$25d82d00$1100a8c0@rspi обсуждение исходный текст |
Ответ на | count(*) optimization ("Nikola Ivacic" <nikola@rs-pi.com>) |
Список | pgsql-sql |
The problem is in other software I use, witch uses count(*) function to display relation properties pgAdmin II phpPgAdmin Nikola ----- Original Message ----- From: "Bruno Wolff III" <bruno@wolff.to> To: "Nikola Ivacic" <nikola@rs-pi.com> Cc: <pgsql-sql@postgresql.org> Sent: Wednesday, January 08, 2003 5:22 PM Subject: Re: [SQL] count(*) optimization > On Wed, Jan 08, 2003 at 17:04:40 +0100, > Nikola Ivacic <nikola@rs-pi.com> wrote: > > Hi > > > > I have trouble executing count(*) statement. > > On a large dataset it takes quite a while to return result. > > Is there any other way to get number of tupples in relation > > or is the only way to optimize count() function to index it? > > Indexes won't help count. > > If you retrieve counts a lot more than you do updates that will change their > value, then you may want to keep the counts in another table and use > triggers to keep them updated. >
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