Re: Select count(*), the sequel

Поиск
Список
Период
Сортировка
От Vitalii Tymchyshyn
Тема Re: Select count(*), the sequel
Дата
Msg-id 4CBBFE2F.3010801@gmail.com
обсуждение исходный текст
Ответ на Select count(*), the sequel  (Mladen Gogala <gogala.mladen@gmail.com>)
Ответы Re: Select count(*), the sequel
Список pgsql-performance
16.10.10 19:51, Mladen Gogala написав(ла):
> There was some doubt as for the speed of doing the select count(*) in
> PostgreSQL and Oracle.
> To that end, I copied the most part of the Oracle table I used before
> to Postgres. Although the copy
> wasn't complete, the resulting table is already significantly larger
> than the table it was copied from. The result still shows that Oracle
> is significantly faster:

Hello.

Did you vacuum postgresql DB before the count(*). I ask this because
(unless table was created & loaded in same transaction) on the first
scan, postgresql has to write hint bits to the whole table. Second scan
may be way faster.

Best regards, Vitalii Tymchyshyn

В списке pgsql-performance по дате отправления:

Предыдущее
От: Samuel Gendler
Дата:
Сообщение: Re: No hash join across partitioned tables?
Следующее
От: Mladen Gogala
Дата:
Сообщение: Re: Select count(*), the sequel