Re: Increasing select max(datecol) from bilkaib where datecol<=date'2008-11-01' and (cr='00' or db='00') speed

Список
Период
Сортировка
От Andrus
Тема Re: Increasing select max(datecol) from bilkaib where datecol<=date'2008-11-01' and (cr='00' or db='00') speed
Дата
Msg-id 498EDF1308A1409E9CE994C83A345BA3@andrusnotebook
обсуждение исходный текст
Ответ на Re: Increasing select max(datecol) from bilkaib where datecol<=date'2008-11-01' and (cr='00' or db='00') speed  ("Vladimir Sitnikov")
Список pgsql-performance
Дерево обсуждения
Increasing select max(datecol) from bilkaib where datecol<=date'2008-11-01' and (cr='00' or db='00') speed  ("Andrus", )
 Re: Increasing select max(datecol) from bilkaib where datecol<=date'2008-11-01' and (cr='00' or db='00') speed  (Matthew Wakeling, )
 Re: Increasing select max(datecol) from bilkaib where datecol<=date'2008-11-01' and (cr='00' or db='00') speed  ("Vladimir Sitnikov", )
  Re: Increasing select max(datecol) from bilkaib where datecol<=date'2008-11-01' and (cr='00' or db='00') speed  (Matthew Wakeling, )
   Re: Increasing select max(datecol) from bilkaib where datecol<=date'2008-11-01' and (cr='00' or db='00') speed  ("Andrus", )
    Re: Increasing select max(datecol) from bilkaib where datecol<=date'2008-11-01' and (cr='00' or db='00') speed  ("Vladimir Sitnikov", )
     Re: Increasing select max(datecol) from bilkaib where datecol<=date'2008-11-01' and (cr='00' or db='00') speed  ("Andrus", )
 Re: Increasing select max(datecol) from bilkaib where datecol<=date'2008-11-01' and (cr='00' or db='00') speed  (hubert depesz lubaczewski, )
  Re: Increasing select max(datecol) from bilkaib wheredatecol<=date'2008-11-01' and (cr='00' or db='00') speed  ("Andrus", )
Vladimir,

>I am afraid PostgreSQL is not smart enough to rewrite query with "or" into
>two separate index scans. There is no way to improve the query
>significantly without rewriting it.
>Note:  for this case indices on (datecol), (cr) and (db) are not very
>helpful.

Thank you very much.
I added you indexes to db and re-write query.
Now it runs fast.

Andrus.


В списке pgsql-performance по дате отправления:

Предыдущее
От: Tomas Vondra
Дата:
Сообщение: Re: Using index for IS NULL query
Следующее
От: "Scott Marlowe"
Дата:
Сообщение: Re: Performance Question