Horton

Re: POC: Sharing record typmods between backends

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Andres Freund <andres@anarazel.de>
Cc: Thomas Munro <thomas.munro@enterprisedb.com>, Dilip Kumar <dilipbalaut@gmail.com>, Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2017-08-23T19:13:30Z
Lists: pgsql-hackers 
On Wed, Aug 23, 2017 at 12:42 PM, Andres Freund <andres@anarazel.de> wrote:
> I don't think that's sufficient. make, and especially check-world,
> should have a decent coverage of the code locally. Without having to
> know about options like force_parallel_mode=regress. As e.g. evidenced
> by the fact that Thomas's latest version crashed if you ran the tests
> that way.  If there's a few lines that aren't covered by the plain
> tests, and more than a few node + parallelism combinations, I'm not
> bothered much. But this is (soon hopefully was) a fairly complicated
> piece of infrastructure - that should be exercised.  If necessary that
> can just be a BEGIN; SET LOCAL force_parallel_mode=on; query with
> blessed descs;COMMIT or whatnot - it's not like we need something hugely
> complicated here.

Yeah, we've been bitten before by changes that seemed OK when run
without force_parallel_mode but misbehaved with that option, so it
would be nice to improve things.  Now, I'm not totally convinced that
just adding a test around blessed tupledescs is really going to help
very much - that option exercises a lot of code, and this is only one
relatively small bit of it.  But I'm certainly not objecting to the
idea.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

Commits

  1. Remove TupleDesc remapping logic from tqueue.c.

  2. Add support for coordinating record typmods among parallel workers.

  3. Improve division of labor between execParallel.c and nodeGather[Merge].c.

  4. Add minimal regression test for blessed record type transfer.

  5. Consolidate the function pointer types used by dshash.c.

  6. Fix unlikely shared memory leak after failure in dshash_create().

  7. Refactor typcache.c's record typmod hash table.

  8. Add a hash_combine function for mixing hash values.

  9. Backpatch introduction of TupleDescAttr(tupdesc, i).

  10. Partially flatten struct tupleDesc so that it can be used in DSM.

  11. Change tupledesc->attrs[n] to TupleDescAttr(tupledesc, n).