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

Jeff Janes <jeff.janes@gmail.com>

From: Jeff Janes <jeff.janes@gmail.com>

To: Robert Haas <robertmhaas@gmail.com>

Cc: Sergey Koposov <koposov@ast.cam.ac.uk>, Florian Pflug <fgp@phlo.org>, Merlin Moncure <mmoncure@gmail.com>, pgsql-hackers@postgresql.org, Stephen Frost <sfrost@snowman.net>

Date: 2012-06-01T00:27:41Z

Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

Improve bulk-insert performance by keeping the current target buffer pinned
- 85e2cedf985b 8.4.0 cited

On Thu, May 31, 2012 at 9:17 AM, Robert Haas <robertmhaas@gmail.com> wrote:
>
> Oh, ho.  So from this we can see that the problem is that we're
> getting huge amounts of spinlock contention when pinning and unpinning
> index pages.
>
> It would be nice to have a self-contained reproducible test case for
> this, so that we could experiment with it on other systems.

I just posted a patch under subject "pgbench--new transaction type"
that introduces a pgbench -P option.

I think that that would do a good job of simulating unique-key
look-ups on the inner side of a nested loop (which is basically what
we have here) and so creating contention on index pages.  Right now I
don't have anything with more than 2 CPUs and 2 is not high enough to
get much contention so I can't post any meaningful numbers.  (pgbench
-P might also be of interest in hash index investigation)

Cheers,

Jeff