Horton

Re: 9.2beta1, parallel queries, ReleasePredicateLocks, CheckForSerializableConflictIn in the oprofile

Jeff Janes <jeff.janes@gmail.com>

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From: Jeff Janes <jeff.janes@gmail.com>
To: Sergey Koposov <koposov@ast.cam.ac.uk>
Cc: Florian Pflug <fgp@phlo.org>, Merlin Moncure <mmoncure@gmail.com>, Robert Haas <robertmhaas@gmail.com>, pgsql-hackers@postgresql.org, Stephen Frost <sfrost@snowman.net>
Date: 2012-05-31T00:46:31Z
Lists: pgsql-hackers

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  1. Improve bulk-insert performance by keeping the current target buffer pinned

On Wed, May 30, 2012 at 4:16 PM, Sergey Koposov <koposov@ast.cam.ac.uk> wrote:

> But the question now is whether there is a *PG* problem here or not, or is
> it Intel's or Linux's problem ? Because still the slowdown was caused by
> locking. If there wouldn't be locking there wouldn't be any problems (as
> demonstrated a while ago by just cat'ting the files in multiple threads).

You cannot have a traditional RDBMS without locking.  From your
description of the problem, I probably wouldn't be using a traditional
database system at all for this, but rather flat files and Perl.  Or
at least, I would partition the data before loading it to the DB,
rather than trying to do it after.

But anyway, is idt_match a fairly static table?  If so, I'd partition
that into 16 tables, and then have each one of your tasks join against
a different one of those tables.  That should relieve the contention
on the index root block, and might have some other benefits as well.

Cheers,

Jeff