Horton

Re: WIP: [[Parallel] Shared] Hash

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Thomas Munro <thomas.munro@enterprisedb.com>
Cc: Rafia Sabih <rafia.sabih@enterprisedb.com>, Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>, Peter Geoghegan <pg@heroku.com>, Haribabu Kommi <kommi.haribabu@gmail.com>, Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2017-03-07T21:41:25Z
Lists: pgsql-hackers 
Hi,

On 2017-03-07 02:57:30 +1300, Thomas Munro wrote:
> I'm not sure why nodeHashjoin.c is doing raw batchfile read/write
> operations anyway; why not use tuplestore.c for that (as
> tuplestore.c's comments incorrectly say is the case)?

Another reason presumably is that using tuplestores would make it harder
to control the amount of memory used - we do *not* want an extra set of
work_mem used here, right?

- Andres

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