Thank you. I'll set work_mem back to 16MB and see
what happens from there.
-Midge
----- Original Message -----
Sent: Saturday, August 20, 2011 9:01
PM
Subject: Re: settings input for
upgrade
On Thu, Aug 18, 2011 at 3:55 PM, Midge Brown <midgems@xxxxxxxxxxxxx>
wrote:
> Here are the changes I made to postgres.conf. The only
differences between
> the conf file for DB1 and those for DB2 & 3
are the port and
> effective_cache_size (which I made slightly smaller
-- 8 GB instead of 10 --
> for the 2 write-heavy DBs). The 600 max
connections are often idle and don't
> get explicitly closed in the
application. I'm looking at connection pooling
> as well.
>
work_mem = 128MB
I'd lower this unless you are certain that something
like 16MB just
isn't gonna get similar performance. Even with mostly
connections
idle, 128M is a rather large work_mem. Remember it's per
sort, per
connection. It can quickly cause the kernel to dump file
cache that
keeps the machine running fast if a couple dozen connections run
a
handful of large sorts at once. What happens is that while things
run
smooth when there's low to medium load, under high load the
machine
will start thrashing trying to allocate too much work_mem and
then
just slow to a crawl.
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