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From: Bruce Momjian <[email protected]>
To: Tom Lane <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: dx k9 <[email protected]>
Subject: Re: [ADMIN] shared_buffers and shmmax
Date: Mon, 15 Dec 2008 18:23:02 -0500 (EST)
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

Tom Lane wrote:
> [ redirecting to pgsql-docs ]
> 
> Valentin Bogdanov <[email protected]> writes:
> >> From: dx k9 <[email protected]>
> >> I'm trying to understand what the documentation means
> >> by bytes per increment, what is the increment supposed to
> >> be bytes, MB, or Kb.
> 
> > shared_buffers is in disk block size, typically 8K, at least that's what it is on Linux platforms. shmmax is quite simply in bytes.
> 
> The table the OP is looking at (table 17.2 in the 8.3 docs) predates
> the ability to specify shared_buffers in KB or MB instead of
> number-of-buffers.  I agree it's not entirely obvious that what it
> means is "multiply your setting in KB/MB by 8400/8192".  Anybody have
> an idea how to clarify things?

I have updated the table title to be clearer.

-- 
  Bruce Momjian  <[email protected]>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +


Attachments:

  [text/x-diff] /rtmp/diff (1023B, 2-%2Frtmp%2Fdiff)
  download | inline diff:
Index: doc/src/sgml/runtime.sgml
===================================================================
RCS file: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v
retrieving revision 1.422
diff -c -c -r1.422 runtime.sgml
*** doc/src/sgml/runtime.sgml	20 Nov 2008 11:48:26 -0000	1.422
--- doc/src/sgml/runtime.sgml	15 Dec 2008 23:22:24 -0000
***************
*** 1087,1093 ****
       <thead>
        <row>
         <entry>Name</>
!        <entry>Approximate multiplier (bytes per increment) as of 8.3</>
        </row>
       </thead>
  
--- 1087,1093 ----
       <thead>
        <row>
         <entry>Name</>
!        <entry>Additional bytes per object, as of 8.3</>
        </row>
       </thead>
  
***************
*** 1119,1125 ****
  
        <row>
         <entry>Fixed space requirements</>
!        <entry>770 kB</entry>
        </row>
       </tbody>
      </tgroup>
--- 1119,1125 ----
  
        <row>
         <entry>Fixed space requirements</>
!        <entry>770 k</entry>
        </row>
       </tbody>
      </tgroup>


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