Horton

Re: Memory-Bounded Hash Aggregation

Jeff Davis <pgsql@j-davis.com>

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From: Jeff Davis <pgsql@j-davis.com>
To: Peter Geoghegan <pg@bowt.ie>
Cc: Heikki Linnakangas <hlinnaka@iki.fi>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, Taylor Vesely <tvesely@pivotal.io>, Adam Lee <ali@pivotal.io>, Melanie Plageman <mplageman@pivotal.io>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2020-02-13T22:48:20Z
Lists: pgsql-hackers

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On Wed, 2020-02-12 at 21:51 -0800, Jeff Davis wrote:
> The new patch is basically just rebased -- a few other very minor
> changes.

I extracted out some minor refactoring of nodeAgg.c that I can commit
separately. That will make the main patch a little easier to review.
Attached.

* split build_hash_table() into two functions
* separated hash calculation from lookup
* changed lookup_hash_entry to return AggStatePerGroup directly instead
of the TupleHashEntryData (which the caller only used to get the
AggStatePerGroup, anyway)

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,