Re: Basic question about indexes/explain

Поиск
Список
Период
Сортировка
От Mario Weilguni
Тема Re: Basic question about indexes/explain
Дата
Msg-id 200210261340.06876.mweilguni@sime.com
обсуждение исходный текст
Ответ на Basic question about indexes/explain  (Terry Yapt <pgsql@technovell.com>)
Ответы Re: Basic question about indexes/explain  (Tom Lane <tgl@sss.pgh.pa.us>)
Список pgsql-performance
Am Samstag, 26. Oktober 2002 12:27 schrieb Terry Yapt:
> Hi all,
>
snip
> I have a basic doubt about indexes...  in the next example:
> But if we have an index with the two colums I am using in the WHERE clause,
> why is the planner using seq scan ?  (Or perhaps it is because too few rows
> in the table ?)....

First of all, you did not analyze your table (at least you did not mention you did). And an index is never a win for
sucha small table. I think the planner is fine here to select a seq scan, because your whole table is only 1 database
page,so it would be no win to check the index here. 

Everything is explained in the manual, check http://developer.postgresql.org/docs/postgres/indexes.html

regards,
    mario weilguni

В списке pgsql-performance по дате отправления:

Предыдущее
От: Terry Yapt
Дата:
Сообщение: Basic question about indexes/explain
Следующее
От: Tom Lane
Дата:
Сообщение: Re: Basic question about indexes/explain