Re: Would my postgresql 8.4.12 profit from doubling RAM?

On Sat, Sep 29, 2012 at 11:27 AM, Alexander Farber
<alexander(dot)farber(at)gmail(dot)com> wrote:
> Hello,
>
> I've finally doubled up RAM to 32 GB for my Quad core
> CentOS 6.3 server and have changed postgresql.conf to
>
> max_connections = 100
> shared_buffers = 4096MB
> work_mem = 16M
>
> But don't see any speed improvement and also 27 GB of
> memory aren't used.... Please see more info + vmstat at
>
> http://serverfault.com/questions/433281/doubled-up-ram-to-32-gb-now-how-to-speed-up-a-lapp-server

I'd suggest turning on persistent connections because you DO use
pgbouncer. It'll reduce connection time and give slightly better
performance. But from reading that page, I don't think you've given
us (or yourself really) enough data to tell you how to improve
performance.

The first thing to do is some simple performance profiling in your php
script. Just add error_log() or whatever it's called in php, with
some timing info in them to see where your time is being spent. If
it's mostly on the db side, we head there, if it's mostly in the php
we look there. At first just put in a couple statements throughout
your script (include things like pid etc so you can trawl your logs
for this later) to get an idea where in general you're spending your
time. Once we get a handle on where most of it is going we'll go from
there.