Re: [HACKERS] Simmultanous Connections (fwd) - Mailing list pgsql-hackers

>   Can anyone here help?
>
>   Vince.
>
>   ---------- Forwarded message ----------
>   Date: Mon, 10 Jan 2000 08:52:06 +0000
>   From: Jude Weaver <exec@shreve.net>
>   To: webmaster@postgresql.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.

-- 
Karl DeBisschop <kdebisschop@alert.infoplease.com>
617.832.0332 (Fax: 617.956.2696)

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