Re: Mac OS X shared_buffers not same as postgresql.conf file

From: Neil Tiffin <neil(at)neiltiffin(dot)com>
To: Guillaume Lelarge <guillaume(at)lelarge(dot)info>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: Mac OS X shared_buffers not same as postgresql.conf file
Date: 2011-09-25 17:13:24
Message-ID: F685A6C4-11D1-453A-9A12-59B181D95AFE@neiltiffin.com
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On Sep 24, 2011, at 4:21 PM, Guillaume Lelarge wrote:

> On Sat, 2011-09-24 at 14:43 -0500, Neil Tiffin wrote:
>> On Sep 24, 2011, at 1:31 PM, Joe Conway wrote:
>>
>>> On 09/23/2011 02:33 PM, Neil Tiffin wrote:
>>>> I have shared_buffers in the config file set for 32 MB and pgAdmin
>>>> reports a value of 32 MB, but pgAdmin also says the current value is
>>>> 4096. Can anyone point me to any docs about why the current value
>>>> may be different than the config value? Temp_buffers are the same
>>>> way, config file 8MB, but current value in pgAdmin is 1024?
>>>
>>> Internally shared_buffers is tracked as number of 8K pages.
>>>
>>> postgres=# show shared_buffers;
>>> shared_buffers
>>> ----------------
>>> 32MB
>>> (1 row)
>>>
>>> postgres=# select setting from pg_settings where name='shared_buffers';
>>> setting
>>> ---------
>>> 4096
>>> (1 row)
>>>
>>> postgres=# select 4096 * 8 / 1024 as MB;
>>> mb
>>> ----
>>> 32
>>> (1 row)
>>>
>>> HTH,
>>
>> Excellent, just what I was looking for. I know there had to be a simple explanation, even though it seems a little retarded that pgAdmin does not point this out.
>
> And how do you get that value from pgAdmin? the config editor gives me
> the value with its unit, so I guess it's not from the config editor.
>

I got the values from selecting in pgAdmin: Tools -> Server Configuration -> postgresql.conf, then I get a table with setting name, value, current value, and comment columns. The 'value' column shows the unit, but the 'current value' column does not, at least on Mac OS X.

Neil

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