Re: which one is faster
От
Mladen Gogala
Тема
Re: which one is faster
Дата
Msg-id
4CC6CA76.1020509@vmsinfo.com
Ответ на
which one is faster (AI Rumman)
Список
Дерево обсуждения
which one is faster AI Rumman <rummandba@gmail.com>
Re: which one is faster Mladen Gogala <mladen.gogala@vmsinfo.com>
Re: which one is faster Szymon Guz <mabewlun@gmail.com>
Re: which one is faster Marcin Mirosław <marcin@mejor.pl>
Re: which one is faster Szymon Guz <mabewlun@gmail.com>
Re: which one is faster Grzegorz Jaśkiewicz <gryzman@gmail.com>
Re: which one is faster Szymon Guz <mabewlun@gmail.com>
Re: which one is faster Grzegorz Jaśkiewicz <gryzman@gmail.com>
Re: which one is faster Szymon Guz <mabewlun@gmail.com>
On 10/26/2010 6:56 AM, AI Rumman wrote: > Which one is faster? > select count(*) from talble > or > select count(id) from table > where id is the primary key. PostgreSQL doesn't utilize the access methods known as "FULL INDEX SCAN" and "FAST FULL INDEX SCAN", so the optimizer will generate the sequential scan in both cases. In other words, PostgreSQL will read the entire table when counting, no matter what. -- Mladen Gogala Sr. Oracle DBA 1500 Broadway New York, NY 10036 (212) 329-5251 www.vmsinfo.com
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