Re: postgresql recommendation memory

On Mon, Nov 11, 2013 at 1:09 AM, Евгений Селявка <evg(dot)selyavka(at)gmail(dot)com> wrote:
> Scott hi, i calculate all of my jdbc pool size. Maximum is 300 connections
> from components wich use jdbc. I don't think that this is a good idea use
> pgbouncer, because our application using spring framework which using jdbc
> and prepared statement. I try to talk with our developer about disabling
> prepared statement in this framework, they don't want do this. Thats why i
> will try to upgrade HW and buy CPU with more core as you say based on
> formula 3-4xcore. But most of this connection is idle. This is a web based
> app not a datawarehouse, thats why all this connection is lightwear.
>
> About my db freeze i set this kernel parameter:
> echo 1048576 > /proc/sys/vm/min_free_kbytes
> echo 80 > /proc/sys/vm/vfs_cache_pressure
>
> And my freeze intervals is steel smaller. I try to dig deeper.

well you can hopefully reduce connections from jdbc pooling then. The
fact that the connections are idle is good.

The problem you run into is what happens when things go into
"overload" I.e. when the db server starts to slow down, more of those
idle connections become not idle. If all 300 are then waiting on the
db server, it will slow to a crawl and eventually fall over.