Re: Estimated resources for a 500 connections instance (VM)

David Gauthier <davegauthierpg(at)gmail(dot)com> writes:

> After looking at some of the factors that can affect this, I think it may
> be important to know that most of the connections will be almost idle (in
> terms of interacting with the DB). The "users" are perl/dbi scripts which
> connect to the DB and spend the vast majority of the time doing things
> other than interacting with the DB. So a connection is consumed, but it's
> not really working very hard with the DB per-se. I am cleaning up some of
> that code by strategically connecting/disconnecting only when a DB
> interaction is required. But for my edification, is it roughly true that 2
> connections working with the DB 100% of the time is equivalent to 20
> connections @ 10% = 200 connections @ 1 % (if you know what I mean) ?

Based on that additional info, I would definitely follow Laurenz's
suggestion. Long time since I used Perl DBI, but I'm pretty sure there
is is support for connection pools or you can use one of the PG
connection pooling solutions.

There is a fixed memory allocation per connection, so 2 connections at
100% is not the same as 20 connections @ 10%.

Using a connection pool is usually the first thing I will setup. If
additional connections are still required, then I would increase the
limit in small jumps - definitely would not go from 100 to 500.

BTW running PG on a virtual is not an issue in itself - this is very
common these days. However, I would ensure you are up-to-date wrt latest
minor release for that version and would use clients with the same
version as the master.

--
Tim Cross