Horton

Parallel Append subplan order instability on aye-aye

Thomas Munro <thomas.munro@gmail.com>

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From: Thomas Munro <thomas.munro@gmail.com>
To: pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2019-05-20T03:36:29Z
Lists: pgsql-hackers 
Hi,

Here's a one-off regression test failure of a sort that commit
624e440a intended to fix.  a_star unexpectedly sorted higher.  I
checked the space weather forecast for this morning but no sign of
solar flares.  More seriously, it did the same in all 3 Parallel
Append queries.  Recent commits look irrelevant.  Could a UDP stats
packet dropped on the floor cause that?  Otherwise maybe you'd need a
weird result from FileSize() to explain it.  Based on log output no
other tests ran around the same time.

https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=aye-aye&dt=2019-05-19%2018%3A30%3A10

-- 
Thomas Munro
https://enterprisedb.com

Commits

  1. ANALYZE a_star and its children to avoid plan instability in tests.

  2. Finish reverting "Insert temporary debugging output in regression tests."

  3. Partially revert "Insert temporary debugging output in regression tests."

  4. Insert temporary debugging output in regression tests.

  5. Improve the heuristic for ordering child paths of a parallel append.