Re: [HACKERS] Simmultanous Connections (fwd)

> Can anyone here help?
>
> Vince.
>
> ---------- Forwarded message ----------
> Date: Mon, 10 Jan 2000 08:52:06 +0000
> From: Jude Weaver <exec(at)shreve(dot)net>
> To: webmaster(at)postgresql(dot)org
> Subject: Simmultanous Connections
>
> We are a company that writes academic software . We are converting our
> software to use either PostgreSQL or MySQL. We are leaning toward
> PostgreSQL, but, I still have several questions.
> I hope someone can answer these for me.
>
> 1. I have read the Q&A for postgreSQL and would like to know the
> difference between a temporary
> and a permanant connection. Do you have a connection when you open
> the database or only when
> the frontend sends a job to the backend? If 32 people are running
> a module that opens a database
> is that 32 connections or will it vary as users read and write to
> the database?

Sounds like she may looking at postgres in PHP - at least PHP uses
that temporary and permanant connection concept. My experience is
that PHP persistent connections are not worth it - the time to
establish a new connection is pretty small, and stale connections can
cause problems.

> 2. I saw in the Q&A that to run more than 32 simmultanous connects could
> be a big drain on our re-
> sources. Our Linux boxes , in general, are Intel 166 to 500s, 128MG
> of RAM and 6.2 to 13 GIG.
> Can anyone tell me roughly how much resources per connection does
> PostgreSQL use?

If an idle psql connection is left open, we're looking at about 1 MB
RAM plus 4MB swap on my linux box.

As I noted above, I'd generally recommend against persistent
connections when there are more than a few users.

Sounds like the machines have the capacity for what sounds like a
fairly small task. Of course, there would generally be only one
server machine, so I would recommend choosing one of the faster ones.
But it should be stable and usable ath eith end of the spectrum, at
least from my experience.

> 3. If I have 90 teachers posting grades at the same time, (the grade
> posting program opens 5 dif-
> ferent databases) and 25 secretaries and administrators poking
> around in assorted databases
> looking at information, will postgresql handle that much traffic?

Postgres should handle that easily.

Just my $0.02 worth. Hope it's helpful.

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Karl DeBisschop <kdebisschop(at)alert(dot)infoplease(dot)com>
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