Re: Partitioning performance: cache stringToNode() of pg_constraint.ccbin

On Friday, June 07, 2013 2:10 AM Noah Misch wrote:
> On Thu, Jun 06, 2013 at 07:02:27PM +0530, Amit Kapila wrote:
> > On Tuesday, June 04, 2013 12:37 AM Noah Misch wrote:
>
> > This patch can give good performance gain in the scenario described
> by you.
> > Infact I had taken the readings with patch, it shows similar gain.
>
> Thanks for testing.
>
> > This patch would increase the relcache size, as for each constraint
> on table
> > it would increase 4 bytes irrespective of whether that can give
> performance
> > benefit or not.
>
> Yep, sizeof(Node *) bytes.

So the memory increase number's would like:

Example for 64-bit m/c
In database, there are 100 tables, each having 2 constraints and 30 live
connections

Size increase = no. of tables * size of (Node*) * number of constraints *
no. of live sessions
= 100 * 8 * 2 * 30
= 46.8K

So if such a memory increase seems reasonable, then I think it would be
really beneficial for the load of data in inherited tables.

If no one has objections on this part, then I think this is really useful
patch for PostgreSQL.

With Regards,
Amit Kapila.