From: "Greg Sabino Mullane" <greg@turnstep.com>
To: pgsql-docs@postgresql.org
Cc: pgsql-hackers@postgresql.org
CC: pgsql-hackers@postgresql.org
Subject: Re: [ADMIN] shared_buffers and shmmax
In-Reply-To: <28167.1216737959@sss.pgh.pa.us>
Date: Thu, 24 Jul 2008 17:54:31 -0000
Message-ID: <3bd4182ebf79bc4a171f08d03d2edb2f@biglumber.com>


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>> shared_buffers is in disk block size, typically 8K

> 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?

Bite the bullet and start showing the buffer settings as a pure number of bytes
everywhere, and get rid of the confusing '8kB' unit in pg_settings? Things like
this don't help our cause:

test=# show shared_buffers;
 shared_buffers
----------------
 24MB
(1 row)

test=# set temp_buffers = '24MB';
SET

test=# show temp_buffers;
 temp_buffers
--------------
 3072

test=# select name, setting from pg_settings where name ~ 'buffers';
      name      | setting
----------------+---------
 shared_buffers | 3072
 temp_buffers   | 3072
 wal_buffers    | 8

test=# show wal_buffers;
 wal_buffers
-------------
 64kB


--
Greg Sabino Mullane greg@turnstep.com
End Point Corporation
PGP Key: 0x14964AC8 200807241351
http://biglumber.com/x/web?pk=2529DF6AB8F79407E94445B4BC9B906714964AC8
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