Horton

Re: [PATCH] Incremental sort (was: PoC: Partial sort)

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Cc: Alvaro Herrera <alvherre@2ndquadrant.com>, James Coleman <jtc331@gmail.com>, Michael Paquier <michael@paquier.xyz>, Rafia Sabih <rafia.pghackers@gmail.com>, Peter Geoghegan <pg@bowt.ie>, Simon Riggs <simon@2ndquadrant.com>, Shaun Thomas <shaun.thomas@2ndquadrant.com>, Dmitry Dolgov <9erthalion6@gmail.com>, Alexander Korotkov <a.korotkov@postgrespro.ru>, PostgreSQL Developers <pgsql-hackers@lists.postgresql.org>, Andreas Karlsson <andreas@proxel.se>
Date: 2020-04-06T22:34:04Z
Lists: pgsql-hackers 
Tomas Vondra <tomas.vondra@2ndquadrant.com> writes:
> On Mon, Apr 06, 2020 at 05:51:43PM -0400, Tom Lane wrote:
>> Well, it's *less* unhappy.  thorntail is showing that the number of
>> workers field is not stable; that will need to be masked.

> Yeah, I've already pushed a fix for that. But there seems to be another
> failure in th explain output. Looking.

I'm kind of unimpressed with that fix, because it guarantees that if
there's any problem with more than 2 workers, this test will never
find it.  I think you should do what I said and arrange to replace
the number-of-workers output with "N".

			regards, tom lane

Commits

  1. Further adjustments to Hashagg EXPLAIN ANALYZE output

  2. Rework EXPLAIN format for incremental sort

  3. Fix typos and improve incremental sort comments

  4. Stabilize incremental_sort tests

  5. Minor improvements in Incremental Sort explain

  6. Consider Incremental Sort paths at additional places

  7. Fix representation of SORT_TYPE_STILL_IN_PROGRESS.

  8. Fix failures in incremental_sort due to number of workers

  9. Fix show_incremental_sort_info with force_parallel_mode

  10. Implement Incremental Sort

  11. Fix handling of "Subplans Removed" field in EXPLAIN output.

  12. Fix EXPLAIN (SETTINGS) to follow policy about when to print empty fields.

  13. Ensure plpgsql result tuples have the right composite type marking.

  14. Propagate sort instrumentation from workers back to leader.

  15. Make new regression test case parallel-safe, and improve its output.

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

  17. Fix inappropriate printing of never-measured times in EXPLAIN.

  18. Fix some infelicities in EXPLAIN output for parallel query plans.