Horton

Re: WIP: [[Parallel] Shared] Hash

Thomas Munro <thomas.munro@enterprisedb.com>

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From: Thomas Munro <thomas.munro@enterprisedb.com>
To: Peter Geoghegan <pg@heroku.com>
Cc: Haribabu Kommi <kommi.haribabu@gmail.com>, Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2017-01-09T22:09:15Z
Lists: pgsql-hackers 
On Sat, Jan 7, 2017 at 9:01 AM, Thomas Munro
<thomas.munro@enterprisedb.com> wrote:
> On Tue, Jan 3, 2017 at 10:53 PM, Thomas Munro
> <thomas.munro@enterprisedb.com> wrote:
>> I will post a new rebased version soon with that and
>> some other nearby problems fixed.
>
> Here is a new WIP patch.

To make this easier to understand and harmonise the logic used in a
few places, I'm now planning to chop it up into a patch series,
probably something like this:

1.  Change existing hash join code to use chunk-based accounting
2.  Change existing hash join code to use a new interface for dealing
with batches
3.  Add shared hash join support, single batch only
4.  Add components for doing shared batch reading (unused)
5.  Add multi-batch shared hash join support

-- 
Thomas Munro
http://www.enterprisedb.com

Commits

  1. Add shared tuplestores.

  2. Remove BufFile's isTemp flag.

  3. Provide DSM segment to ExecXXXInitializeWorker functions.

  4. Optimize joins when the inner relation can be proven unique.

  5. Fix failure to use clamp_row_est() for parallel joins.

  6. Document lack of validation when attaching foreign partitions.

  7. Fix inclusions of c.h from .h files.

  8. Fix inclusions of postgres_fe.h from .h files.

  9. Bring plpgsql into line with header inclusion policy.

  10. Document intentional violations of header inclusion policy.

  11. Shut down Gather's children before shutting down Gather itself.

  12. btree: Support parallel index scans.

  13. Add explicit ORDER BY to a few tests that exercise hash-join code.

  14. Revise hash join code so that we can increase the number of batches

  15. Rewrite hash join to use simple linked lists instead of a