Re: How does the planner execute unions?

От: Bruno Wolff III
Тема: Re: How does the planner execute unions?
Дата: ,
Msg-id: 20050826204554.GB11078@wolff.to
(см: обсуждение, исходный текст)
Ответ на: How does the planner execute unions?  (Chris Hoover)
Список: pgsql-performance

On Fri, Aug 26, 2005 at 16:14:18 -0400,
  Chris Hoover <> wrote:
> Hopefully a quick question.
>
> In 7.3.4, how does the planner execute a query with union alls in it?
>
> Does it execute the unions serially, or does it launch a "thread" for
> each union (or maybe something else entirely).

Postgres doesn't have parallel execution of parts of queries. So it is
going to do one part followed by the other part.


В списке pgsql-performance по дате сообщения:

От: Michael Fuhr
Дата:
Сообщение: Re: Weird performance drop after VACUUM
От: Mark Kirkwood
Дата:
Сообщение: Re: Limit + group + join