Horton

Re: pgsql: Add parallel-aware hash joins.

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Thomas Munro <thomas.munro@enterprisedb.com>
Cc: Andres Freund <andres@anarazel.de>, pgsql-committers <pgsql-committers@postgresql.org>
Date: 2018-01-04T16:00:24Z
Lists: pgsql-hackers 
I wrote:
> I ran a couple dozen test cycles on gaur without a failure.  That's
> not enough to really prove anything, but it's more successes than I was
> getting before.  I pushed the patch so we can see what the rest of the
> buildfarm thinks.

The early returns indicate that that problem is fixed; but now that the
noise level is down, it's possible to see that brolga is showing an actual
crash in the PHJ test, perhaps one time in four.  So we're not out of
the woods yet.  It seems to consistently look like this:

2017-12-21 17:34:52.092 EST [2252:4] LOG:  background worker "parallel worker" (PID 3584) was terminated by signal 11
2017-12-21 17:34:52.092 EST [2252:5] DETAIL:  Failed process was running: select count(*) from foo
	  left join (select b1.id, b1.t from bar b1 join bar b2 using (id)) ss
	  on foo.id < ss.id + 1 and foo.id > ss.id - 1;
2017-12-21 17:34:52.092 EST [2252:6] LOG:  terminating any other active server processes


Also, what the devil is happening on skink?

			regards, tom lane

Commits

  1. Update obsolete sentence in README.parallel.

  2. Rewrite ConditionVariableBroadcast() to avoid live-lock.

  3. Tweak parallel hash join test case in hopes of improving stability.

  4. Rename pg_rewind's copy_file_range() to avoid conflict with new linux syscall.

  5. Fix some minor errors in new PHJ code.

  6. Fix EXPLAIN ANALYZE output for Parallel Hash.

  7. Fix rare assertion failure in parallel hash join.

  8. Cancel CV sleep during subtransaction abort.

  9. Add parallel-aware hash joins.

  10. Fix EXPLAIN ANALYZE of hash join when the leader doesn't participate.

  11. Add some regression tests that exercise hash join code.