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Re: optimizing selects on time-series data in Pg

From: Sean Chittenden <sean(at)chittenden(dot)org>
To: Aditya <aditya(at)grot(dot)org>
Cc: sfpug(at)postgresql(dot)org
Subject: Re: optimizing selects on time-series data in Pg
Date: 2003-08-12 19:07:28
Message-ID: 20030812190728.GA82365@perrin.int.nxad.com (view raw or flat)
Thread:
Lists: sfpug
> > > >   shared_buffers = 128        # 2*max_connections, min 16 (default 64)
> > > >   ...
> > > >   #effective_cache_size = 1000  # default in 8k pages
> > > 
> > > You could certainly stand to raise these, unless your system is low
> > > on RAM ...
> > 
> > Using /bin/sh, plop the following in to determine your
> > effective_cache_size:
> > 
> > echo "effective_cache_size = $((`sysctl -n vfs.hibufspace` / 8192))"
> 
> Thanks for that -- it shows:
> 
>   effective_cache_size = 7752
> 
> when I run it. That's a third smaller than what Josh recommended:

...

'ya know, that'd be a whicked cool patch to hack out: backtick support
in postgresql.conf... hrm...  from my TODO:

Add backtick support for postgresql.conf:
    I want to be able to do stuff like:

    effective_cache_size = `$((\`sysctl -n vfs.hibufspace\` / 8192))`

    To have postgresql.conf files be able to automatically tune
    themselves on startup.  What would likely need to happen would be
    some kind of processor (called by pg_ctl, most likely) that would
    run over the postgresql.conf file on startup, execute the
    backtick'ed areas to generate a new postgresql.conf that is static
    that the postmaster actually uses.

-sc

-- 
Sean Chittenden

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Subject: Re: optimizing selects on time-series data in Pg
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