Horton

Re: explain analyze output with parallel workers - question about meaning of information for explain.depesz.com

Thomas Munro <thomas.munro@enterprisedb.com>

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From: Thomas Munro <thomas.munro@enterprisedb.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Amit Kapila <amit.kapila16@gmail.com>, Hubert Lubaczewski <depesz@depesz.com>, pgsql-hackers mailing list <pgsql-hackers@postgresql.org>
Date: 2017-12-07T21:00:12Z
Lists: pgsql-hackers 
On Fri, Dec 8, 2017 at 7:36 AM, Robert Haas <robertmhaas@gmail.com> wrote:
> On Wed, Dec 6, 2017 at 1:05 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:
>> Right and seeing that I have prepared the patch (posted above [1])
>> which fixes it such that it will resemble the non-parallel case.
>
> Long story short, I like the patch.

LGTM.  There might be an argument for clearing the instrumentation
every time on the basis that you might finish up keeping data from a
non-final loop when a worker opted not to do anything in the final
loop, but I'm not going to make that argument because I don't think it
matters.   The patch makes the tests in
test-hash-join-rescan-instr-v1.patch pass (from my previous message).
Please also consider that test patch for commit.

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

Commits

  1. Back-port fix for accumulation of parallel worker instrumentation.

  2. Test instrumentation of Hash nodes with parallel query.

  3. Try again to fix accumulation of parallel worker instrumentation.

  4. Revert "Fix accumulation of parallel worker instrumentation."

  5. Fix accumulation of parallel worker instrumentation.