Re: Question on REINDEX

От: Tom Lane
Тема: Re: Question on REINDEX
Дата: ,
Msg-id: 23413.1113935675@sss.pgh.pa.us
(см: обсуждение, исходный текст)
Ответ на: Re: Question on REINDEX  (Alvaro Herrera)
Список: pgsql-performance

Скрыть дерево обсуждения

Question on REINDEX  (Bill Chandler, )
 Re: Question on REINDEX  (Josh Berkus, )
  Re: Question on REINDEX  (Tom Lane, )
 Re: Question on REINDEX  (Bruno Wolff III, )
 Re: Question on REINDEX  ("Tambet Matiisen", )
  Re: Question on REINDEX  (Tom Lane, )
   Re: Question on REINDEX  (Alvaro Herrera, )
    Re: Question on REINDEX  (Tom Lane, )
  Re: Question on REINDEX  (Josh Berkus, )
   Re: Question on REINDEX  (Tom Lane, )
    Re: Question on REINDEX  (Josh Berkus, )
     Re: Question on REINDEX  (Tom Lane, )

Alvaro Herrera <> writes:
> Am I right in thinking that vacuum does at least two passes: one
> front-to-back to find removable tuples, and other back-to-front for
> movement?

VACUUM FULL, yes.  VACUUM only does the first one.

> I know maintenance_work_mem is used for storing TIDs of to-be-moved
> tuples for index cleanup ... how does it relate to the above?

TIDs of to-be-deleted tuples, actually.  Movable tuples aren't stored,
they're just found on-the-fly during the back-to-front pass.

            regards, tom lane


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