Horton

Re: [HACKERS] [PATCH] Incremental sort

Antonin Houska <ah@cybertec.at>

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From: Antonin Houska <ah@cybertec.at>
To: Alexander Korotkov <a.korotkov@postgrespro.ru>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2017-11-22T10:22:30Z
Lists: pgsql-hackers 
Alexander Korotkov <a.korotkov@postgrespro.ru> wrote:

> Antonin Houska <ah@cybertec.at> wrote:

> >  * ExecIncrementalSort()
> >
> >  ** if (node->tuplesortstate == NULL)
> > 
> >  If both branches contain the expression
> > 
> >  node->groupsCount++;
> > 
> >  I suggest it to be moved outside the "if" construct.
> 
> Done.

One more comment on this: I wonder if the field isn't incremented too
early. It seems to me that the value can end up non-zero if the input set is
to be empty (not sure if it can happen in practice).

And finally one question about regression tests: what's the purpose of the
changes in contrib/postgres_fdw/sql/postgres_fdw.sql ? I see no
IncrementalSort node in the output.

-- 
Antonin Houska
Cybertec Schönig & Schönig GmbH
Gröhrmühlgasse 26
A-2700 Wiener Neustadt
Web: http://www.postgresql-support.de, http://www.cybertec.at

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.