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Re: shared_buffers > 284263 on OS X

From: Guido Neitzer <lists(at)event-s(dot)net>
To: Brendan Duddridge <brendan(at)clickspace(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: shared_buffers > 284263 on OS X
Date: 2006-11-27 07:04:38
Message-ID: BB09140E-C659-419C-BF49-CC8D3AA1CAD5@event-s.net (view raw or flat)
Thread:
Lists: pgsql-performance
Am 27.11.2006 um 04:20 schrieb Brendan Duddridge:

> I think the main issue is that we can't seem to get PostgreSQL  
> compiled for 64 bit on OS X on an Xserve G5. Has anyone done that?
>
> We have 8 GB of RAM on that server, but we can't seem to utilize it  
> all. At least not for the shared_buffers setting.

One VERY ugly idea is: if you have your stuff in more than one db,  
let two PostgreSQL installations run on the same machine and put some  
databases on one and others on the second installation (on different  
ports and different data directories of course) and give either one  
the 2GB shared mem you like. So you can use the 50% of the available  
RAM.

I don't know whether Mac OS X itself is able to handle a larger  
amount of shared memory but I believe it can.

But nevertheless this is only a very ugly workaround on a problem  
that shouldn't exist. The correct way would be to get a 64 Bit binary  
of PostgreSQL - which I wasn't able to create.

But, be aware of another thing here: As far as I have read about 64  
Bit applications on G5, these apps are definitely slower than their  
32 bit counterparts (I'm currently on the train so I can't be more  
precise here without Google ...). Was it something with not enough  
registers in the CPU? Something like that ... So it might be, that  
the 64 bit version is able to use more shared memory but is slower  
than the 32 bit version and you come out with the same performance.  
Nobody knows ...

cug

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Subject: Re: shared_buffers > 284263 on OS X
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