From: Bruce Momjian <pgman@candle.pha.pa.us>
Message-Id: <200512070536.jB75aCm14675@candle.pha.pa.us>
Subject: Re: Lazy vacuum space reclaiming
In-Reply-To: <20051014185133.GR23883@pervasive.com>
To: "Jim C. Nasby" <jnasby@pervasive.com>
Date: Wed, 7 Dec 2005 00:36:12 -0500 (EST)
CC: pgsql-docs@postgresql.org
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Adjustment patch applied.  Thanks.

---------------------------------------------------------------------------

Jim C. Nasby wrote:
> >From http://www.postgresql.org/docs/8.0/interactive/maintenance.html:
> 
> "The first form, known as "lazy vacuum" or just VACUUM, marks expired
> data in tables and indexes for future reuse; it does not attempt to
> reclaim the space used by this expired data immediately. Therefore, the
> table file is not shortened, and any unused space in the file is not
> returned to the operating system."
> 
> This isn't completely accurate, though I'm not sure what a good wording
> would be. Maybe:
> 
> "The first form, known as "lazy vacuum" or just VACUUM, marks expired
> data in tables and indexes for future reuse. It only reclaims expired
> space from tables if it is at the end of the table, and no empty space
> is reclaimed from indexes."
> -- 
> Jim C. Nasby, Sr. Engineering Consultant      jnasby@pervasive.com
> Pervasive Software      http://pervasive.com    work: 512-231-6117
> vcard: http://jim.nasby.net/pervasive.vcf       cell: 512-569-9461
> 
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-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
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Index: doc/src/sgml/maintenance.sgml
===================================================================
RCS file: /cvsroot/pgsql/doc/src/sgml/maintenance.sgml,v
retrieving revision 1.51
diff -c -c -r1.51 maintenance.sgml
*** doc/src/sgml/maintenance.sgml	4 Nov 2005 23:14:00 -0000	1.51
--- doc/src/sgml/maintenance.sgml	7 Dec 2005 05:35:08 -0000
***************
*** 141,151 ****
      command. The first form, known as <quote>lazy vacuum</quote> or
      just <command>VACUUM</command>, marks expired data in tables and
      indexes for future reuse; it does <emphasis>not</emphasis> attempt
!     to reclaim the space used by this expired data
!     immediately. Therefore, the table file is not shortened, and any
!     unused space in the file is not returned to the operating
!     system. This variant of <command>VACUUM</command> can be run
!     concurrently with normal database operations.
     </para>
  
     <para>
--- 141,152 ----
      command. The first form, known as <quote>lazy vacuum</quote> or
      just <command>VACUUM</command>, marks expired data in tables and
      indexes for future reuse; it does <emphasis>not</emphasis> attempt
!     to reclaim the space used by this expired data unless the space is
!     at the end of the table and an exclusive lock can be obtained easily
!     on the table. Unused space at the start or middle of the file does
!     not result in the file being shortened and space returned to the
!     operating system. This variant of <command>VACUUM</command> can be
!     run concurrently with normal database operations.
     </para>
  
     <para>

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