Re: Disable result buffering to frontend clients

From: Richard Huxton <dev(at)archonet(dot)com>
To: Konstantinos Krikellas <K(dot)Krikellas(at)sms(dot)ed(dot)ac(dot)uk>
Cc: pgsql-performance <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Disable result buffering to frontend clients
Date: 2007-02-22 11:12:11
Message-ID: 45DD7A8B.3040001@archonet.com
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-performance

Konstantinos Krikellas wrote:
> Hi,
>
> I am trying to execute some queries in PostgreSQL that produce a large
> number of results and I do not want to display the output (redirect it
> to /dev/null). I have tried the psql client with \o /dev/null option,
> JDBC and libpq functions, but all of them have to buffer totally the
> result before redirecting it. Is there any way to disable result
> buffering, either on the client or on the server side?

Well, you could use a cursor, but that could change the plan (I believe
it favours plans that return the first result quickly).

You could have a function that used FOR-IN-EXECUTE to run a query for
you then just loop through the results, doing nothing. That would keep
everything server-side.

If you really want to duplicate all the query costs except client-side
buffering, the simplest might be to just hack the libpq source to
discard any query results rather than buffering them - shouldn't be too
difficult.

--
Richard Huxton
Archonet Ltd

In response to

Browse pgsql-performance by date

  From Date Subject
Next Message Gabriel Biberian 2007-02-22 18:11:42 slow update on 1M rows (worse with indexes)
Previous Message Konstantinos Krikellas 2007-02-22 11:02:50 Disable result buffering to frontend clients