Horton

Re: Postgres 11 release notes

Bruce Momjian <bruce@momjian.us>

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From: Bruce Momjian <bruce@momjian.us>
To: David Rowley <david.rowley@2ndquadrant.com>
Cc: Amit Langote <amitlangote09@gmail.com>, Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2018-05-23T02:41:21Z
Lists: pgsql-hackers 
On Wed, May 23, 2018 at 02:06:15PM +1200, David Rowley wrote:
> On 23 May 2018 at 13:18, Bruce Momjian <bruce@momjian.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.

I just suspected they would use the same algorithm.

> 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!

OK.

-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

+ As you are, so once was I.  As I am, so you will be. +
+                      Ancient Roman grave inscription +

Commits

  1. doc: update PG 11 release notes

  2. Fix misspelled pg_trgm contrib name in PostgreSQL 11 release notes

  3. Doc: clarify release note text about v11's new window function features.

  4. Improve wording of release notes item

  5. Fix typos in release notes

  6. Doc: preliminary list of PG11 major features.

  7. Make numeric power() handle NaNs according to the modern POSIX spec.

  8. Various improvements of skipping index scan during vacuum technics

  9. Revert back-branch changes in power()'s behavior for NaN inputs.

  10. Avoid wrong results for power() with NaN input on more platforms.

  11. Avoid wrong results for power() with NaN input on some platforms.

  12. Skip full index scan during cleanup of B-tree indexes when possible

  13. Rewrite the code that applies scan/join targets to paths.

  14. Postpone generate_gather_paths for topmost scan/join rel.

  15. Add casts from jsonb

  16. Make plpgsql use its DTYPE_REC code paths for composite-type variables.

  17. Don't allow VACUUM VERBOSE ANALYZE VERBOSE.

  18. Pass InitPlan values to workers via Gather (Merge).

  19. Account for the effect of lossy pages when costing bitmap scans.

  20. Allow no-op GiST support functions to be omitted.

  21. Rearm statement_timeout after each executed query.

  22. Push limit through subqueries to underlying sort, where possible.