Re: optimizing selects on time-series data in Pg

> > > > 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