Horton

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

Tomas Vondra <tomas.vondra@2ndquadrant.com>

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From: Tomas Vondra <tomas.vondra@2ndquadrant.com>
To: James Coleman <jtc331@gmail.com>
Cc: Andreas Karlsson <andreas@proxel.se>, 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>, Tom Lane <tgl@sss.pgh.pa.us>, PostgreSQL Developers <pgsql-hackers@lists.postgresql.org>, Alvaro Herrera <alvherre@2ndquadrant.com>
Date: 2020-03-23T02:38:51Z
Lists: pgsql-hackers 
On Sun, Mar 22, 2020 at 10:05:50PM -0400, James Coleman wrote:
>On Sun, Mar 22, 2020 at 8:54 PM Andreas Karlsson <andreas@proxel.se> wrote:
>>
>> On 3/23/20 1:33 AM, James Coleman wrote:
>> > So on the face of it we have a bit of a no-win situation. The function
>> > tuple_sort_method_name returns a const, but lappend wants a non-const.
>> > I'm not sure what the project style preference is here: we could cast
>> > the result as (char *) to drop the const qualifier, but that's frowned
>> > upon some places. Alternatively we could make a new non-const copy of
>> > string. Which is preferable in the postgres project style?
>>
>> The PostgreSQL has places where const is explicitly casted away with the
>> unconstify() macro, so unless you can find a better solution that is
>> probably an ok option.
>
>Thanks, that's exactly what I need!
>

Yeah, sorry I forgot to mention/fix the warning in the last review round.

BTW I think the comment for pathkeys_useful_for_ordering() needs
updating, it still claims it's all-or-nothing affair, but that's no
longer true I think.


regards

-- 
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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.