Re: PgPool changes WAS: PostgreSQL clustering VS MySQL

From: "Peter Darley" <pdarley(at)kinesis-cem(dot)com>
To: <josh(at)agliodbs(dot)com>, Ragnar Hafstað <gnari(at)simnet(dot)is>
Cc: <pgsql-performance(at)postgresql(dot)org>, "Tatsuo Ishii" <t-ishii(at)sra(dot)co(dot)jp>
Subject: Re: PgPool changes WAS: PostgreSQL clustering VS MySQL
Date: 2005-01-25 16:49:58
Message-ID: PDEOIIFFBIAABMGNJAGPKEPGDLAA.pdarley@kinesis-cem.com
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Josh,

Please excuse how my client quotes things...

> Are there ones that you use which might use several different connections to
> send a series of queries from a single web-user, less than 5 seconds apart?

Using Apache/Perl I often have a situation where we're sending several queries from the same user (web client) within seconds, or even simultaneously, that use different connections.

When someone logs in to our system they get a frameset that has 5 windows, each of which is filled with data from queries. Since the pages in the frames are requested separately by the client the system doesn't insure that they go to the same process, and subsequently, that they're not served by the same db connection.

Session information is stored in the database (so it's easily persistent across server processes), so it would be bad if a request for a page was served by a db server that didn't yet have information about the user (such as that they're logged in, etc.).

If we ever have enough traffic to warrant it, we're going to go to a load balancer that passes requests to different identical web servers, at which point we won't even be getting requests from the same machine, much less the same connection.

Thanks,
Peter Darley

-----Original Message-----
From: pgsql-performance-owner(at)postgresql(dot)org
[mailto:pgsql-performance-owner(at)postgresql(dot)org]On Behalf Of Josh Berkus
Sent: Monday, January 24, 2005 3:46 PM
To: Ragnar Hafstað
Cc: pgsql-performance(at)postgresql(dot)org; Tatsuo Ishii
Subject: Re: [PERFORM] PgPool changes WAS: PostgreSQL clustering VS
MySQL

Ragnar,

> note that these sometimes do not provide connection pooling as such,
> just persistent connections (Apache::DBI)

Yes, right.

> no. you can only count on web-server-process==connection, but not
> web-user==connection, unless you can garantee that the same user
> client always connects to same web-server process.

Are there ones that you use which might use several different connections to
send a series of queries from a single web-user, less than 5 seconds apart?

--
--Josh

Josh Berkus
Aglio Database Solutions
San Francisco

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