Horton

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

James Coleman <jtc331@gmail.com>

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From: James Coleman <jtc331@gmail.com>
To: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Cc: 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: 2020-03-05T22:01:06Z
Lists: pgsql-hackers 
On Tue, Jan 21, 2020 at 9:37 AM James Coleman <jtc331@gmail.com> wrote:

> That being said, the patch also needs some more work on improving
> EXPLAIN ANALYZE output (perhaps min/max/mean or median of
> memory usage number of groups in each sort mode), and I think it's far
> more feasible that I can tackle that piecemeal before the next CF.
>

I'm looking at this now, and realized that at least for parallel plans the
current patch tracks the tuplesort instrumentation whether or not an
EXPLAIN ANALYZE is in process.

Is this fairly standard for executor nodes? Or is it expected to condition
some of this tracking based on whether or not an ANALYZE is running?

I'm found EXEC_FLAG_EXPLAIN_ONLY but no parallel for analyze. Similarly the
InstrumentOption bit flags on the executor state seems to indicate whether
specific ANALYZE options should be enabled, but I haven't yet seen anything
conditioned solely on whether an ANALYZE is in flight. Could someone point
me in the right direction is this is expected?

Thanks,
James

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.