Re: Postgres 11 release notes

On 23 May 2018 at 13:18, Bruce Momjian <bruce(at)momjian(dot)us> wrote:
> On Mon, May 21, 2018 at 07:34:18PM +1200, David Rowley wrote:
>> I've been working a bit in this area over the past few weeks and with
>> PG11 I measured a single INSERT into a 10k RANGE partitioned table at
>> just 84 tps (!), while inserting the same row into a non-partitioned
>> table was about 11.1k tps. I have patches locally that take this up to
>> ~9.8k tps, which I'll submit for PG12. I'm unsure if we should be
>
> Yikes! I think the question is whether we need to _remove_ the item I
> just posted that is already in the release notes:
>
> Allow faster partition elimination during query processing (Amit
> Langote, David Rowley, Dilip Kumar)
>
> This speeds access to partitioned tables with many partitions.

Well, partition elimination/pruning and tuple routing are not the same
thing. Pruning saves us scanning partitions that can't contain
matching tuples, whereas routing finds a home for a specific tuple.

Amit's work to improve partition elimination certainly is much faster
than constraint exclusion. It's not the last thing we'll ever do to
speed up the planning of queries for partitioned tables but it is a
very good start, and without it, run-time pruning would not be
possible.

I'd say the release notes in this regard don't claim anything that's
untrue. They look fine to me. Thanks for working on them!

--
David Rowley http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services