Re: Win32 Backend Cash - pre-existing shared memory block is still in use - Mailing list pgsql-general

From Scott Marlowe
Subject Re: Win32 Backend Cash - pre-existing shared memory block is still in use
Date
Msg-id AANLkTikwg2OtTR3r+O0s-yG51VV701kG8pAni8VLP8bv@mail.gmail.com
Whole thread Raw
In response to Re: Win32 Backend Cash - pre-existing shared memory block is still in use  (Jeremy Palmer <JPalmer@linz.govt.nz>)
List pgsql-general
On Tue, Aug 24, 2010 at 11:21 PM, Jeremy Palmer <JPalmer@linz.govt.nz> wrote:
> Thanks. So can you explain why 512mb is bad decision here given that I only have 3.7GB of RAM?

Because it's per session.  Even with just a hand ful of processes
running you can chew up most of your memory real fast.  Also, win32
pgsql is limited to 3Gig total memory in use.

> The reason why I want the temp_buffers set so high is because this server is used for large data warehousing type
queries.The server has very few sessions simultaneously running on it, but each session can create large temp tables. 

Start low.  Test, benchmark.  Increase in steps, benchmark again.  See
where performance stops getting better, or the server starts crashing,
back off.  It's pretty standard testing methodology.

It's a very common mistake for people to try to get postgresql to use
as much memory as possible, when quite often letting the OS use a fair
chunk for caching gives as good or better performance.

pgsql-general by date:

Previous
From: Jeremy Palmer
Date:
Subject: Re: Win32 Backend Cash - pre-existing shared memory block is still in use
Next
From: Scott Marlowe
Date:
Subject: Re: Win32 Backend Cash - pre-existing shared memory block is still in use