Horton

Re: Memory-Bounded Hash Aggregation

Jeff Davis <pgsql@j-davis.com>

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From: Jeff Davis <pgsql@j-davis.com>
To: Andres Freund <andres@anarazel.de>
Cc: Tomas Vondra <tomas.vondra@2ndquadrant.com>, Melanie Plageman <melanieplageman@gmail.com>, Heikki Linnakangas <hlinnaka@iki.fi>, Taylor Vesely <tvesely@pivotal.io>, Adam Lee <ali@pivotal.io>, Melanie Plageman <mplageman@pivotal.io>, Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2020-03-12T06:55:35Z
Lists: pgsql-hackers

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On Wed, 2020-02-26 at 19:14 -0800, Jeff Davis wrote:
> Rebased on your change. This simplified the JIT and interpretation
> code
> quite a bit.

Attached another version.

 * tweaked EXPLAIN output some more
 * rebased and cleaned up
 * Added back the enable_hashagg_disk flag (defaulting to on). I've
gone back and forth on this, but it seems like a good idea to have it
there. So now there are a total of two GUCs: enable_hashagg_disk and
enable_groupingsets_hash_disk

Unless I (or someone else) finds something significant, this is close
to commit.

Regards,
     Jeff Davis

Commits

  1. Fix costing for disk-based hash aggregation.

  2. Fixes for Disk-based Hash Aggregation.

  3. Disk-based Hash Aggregation.

  4. Extend ExecBuildAggTrans() to support a NULL pointer check.

  5. Save calculated transitionSpace in Agg node.

  6. Minor refactor of nodeAgg.c.

  7. Logical Tape Set: lazily allocate read buffer.

  8. Introduce TupleHashTableHash() and LookupTupleHashEntryHash().

  9. Logical Tape Set: use min heap for freelist.

  10. Fix comments in execGrouping.c

  11. Avoid integer overflow while sifting-up a heap in tuplesort.c.

  12. Make the overflow guards in ExecChooseHashTableSize be more protective.

  13. Improve performance of our private version of qsort. Per recent testing,