Re: [despammed] question about index

Поиск
Список
Период
Сортировка
От Andreas Kretschmer
Тема Re: [despammed] question about index
Дата
Msg-id 20041216141557.GA17096@Pinguin.wug-glas.de
обсуждение исходный текст
Ответ на Re: [despammed] question about index  (Bruno Wolff III <bruno@wolff.to>)
Список pgsql-sql
am  16.12.2004, um  8:10:25 -0600 mailte Bruno Wolff III folgendes:
> On Thu, Dec 16, 2004 at 12:01:39 +0100,
>   Andreas Kretschmer <akretschmer@despammed.com> wrote:
> > > 
> > > considering that almost 70% of the rows will be with 'VALUE1', 20%
> > > will be with 'VALUE2' and 10% will be with 'VALUE3' on the average.
> > > 
> > > should I create an index to speedup the counts or not ?
> > 
> > Yes.
> 
> Indexes will probably not help in this case. Even when looking at 10% of
> the rows, a sequential scan is still going to be faster than an index
> scan in most cases.

Okay.


Andreas
-- 
Andreas Kretschmer    (Kontakt: siehe Header)              Tel. NL Heynitz:  035242/47212
GnuPG-ID 0x3FFF606C http://wwwkeys.de.pgp.net===    Schollglas Unternehmensgruppe    === 


В списке pgsql-sql по дате отправления:

Предыдущее
От: Bruno Wolff III
Дата:
Сообщение: Re: [despammed] question about index
Следующее
От: "Yudie"
Дата:
Сообщение: plpgsql.. SELECT INTO ... WHERE FIELD LIKE