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: 2020-02-27T03:14:18Z
Lists: pgsql-hackers

Attachments

On Mon, 2020-02-24 at 15:29 -0800, Andres Freund wrote:
> On 2020-02-22 11:02:16 -0800, Jeff Davis wrote:
> > On Sat, 2020-02-22 at 10:00 -0800, Andres Freund wrote:
> > > Both patches, or just 0013? Seems the earlier one might make the
> > > addition of the opcodes you add less verbose?
> > 
> > Just 0013, thank you. 0008 looks like it will simplify things.
> 
> Pushed 0008.

Rebased on your change. This simplified the JIT and interpretation code
quite a bit.

Also:
* caching the compiled expressions so I can switch between the variants
cheaply
* added "Planned Partitions" to explain output
* included tape buffers in the "Memory Used" output
* Simplified the way I try to track memory usage and trigger spilling. 
* Reset hash tables always rather than rebuilding them from scratch.

I will do another round of performance tests and see if anything
changed from last time.

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,