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Re: connections

From: "Dave Page" <dpage(at)pgadmin(dot)org>
To: "Roberts, Jon" <Jon(dot)Roberts(at)asurion(dot)com>
Cc: pgadmin-hackers <pgadmin-hackers(at)postgresql(dot)org>
Subject: Re: connections
Date: 2008-04-21 06:27:40
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Lists: pgadmin-hackers
On Sun, Apr 20, 2008 at 6:00 PM, Dave Page <dpage(at)pgadmin(dot)org> wrote:
> On Fri, Apr 18, 2008 at 7:30 PM, Roberts, Jon <Jon(dot)Roberts(at)asurion(dot)com> wrote:
> I'm awaiting confirmation from the lead architect, but I believe that
> a single connection from pgAdmin will result in 1 connection to each
> node in the cluster in GridSQL. However I believe there is also a
> certain amount of pooling going on so I don't believe it's such a
> problem. Besides.... that may be 16 connections in a 16 node system,
> but each of those is a complete PostgreSQL/EnterpriseDB server capable
> of handling as many connections as it could if it were a standalone
> server (which could be hundreds or thousands), so it's no more an
> issue than if you had a single server.

The word from the GridSQL guru is:

I am not sure I understand why he has so many connections because each
segment should be on a different host. Maybe they have something set
up where there are multiple logical nodes (er, segments) running on a
single postmaster instance.

Maybe that further explodes if each segment creates a connection to
every other one and persists it.

In GridSQL, we have a pool of connections that are used, starting with
5 for each underlying node. These are shared amongst the users, unless
somethings stateful happens in which case the underlying connection
needs to become persistent for a user session. We also have an extra
connection for the metadata database, and some vestiges of old code
for a pool of "coordinator" connections, but they are not used for
most queries.

Anyway, the bottom line is, GridSQL will not consume as many
connections as in the Greenplum case.

Dave Page
EnterpriseDB UK:

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