Horton

Re: pgsql: Add parallel-aware hash joins.

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Robert Haas <robertmhaas@gmail.com>, Thomas Munro <thomas.munro@enterprisedb.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2018-01-04T20:47:41Z
Lists: pgsql-hackers 
On 2018-01-04 15:16:15 -0500, Tom Lane wrote:
> Andres Freund <andres@anarazel.de> writes:
> > On 2018-01-04 11:20:33 -0800, Andres Freund wrote:
> >> Some packages on skink have been upgraded. It appears that there either
> >> was a libc or valgrind change that made valgrind not recognize that a
> >> pointer of 0 might not point anywhere :(
> 
> > ==5718== Invalid write of size 8
> > ==5718==    at 0x40E3DD: ExecInterpExpr (execExprInterp.c:1117)
> > ==5718==    by 0x40F5E9: ExecInterpExprStillValid (execExprInterp.c:1788)
> > ==5718==    by 0xE6B0409: ExecEvalExpr (executor.h:282)
> 
> Are those line numbers supposed to match current HEAD?

Well, 3e68686e2c55799234ecd020bd1621f913d65475, but that's pretty
close.

But I think it was just the result of a somehow not entirely clean
build, with plpgsql not being rebuilt when necessary. Not sure why/how,
but at least that means the epoll_pwait() suppression likely revive
skink to some degree.

I made sure that the valgrind version isn't affected (from mid last
year). After a forced rebuild survives a bit longer, but also encounters

==13750== Conditional jump or move depends on uninitialised value(s)
==13750==    at 0x6BA888C: __wcsnlen_avx2 (strlen-avx2.S:103)
==13750==    by 0x6AF2FF1: wcsrtombs (wcsrtombs.c:104)
==13750==    by 0x6A88A40: wcstombs (wcstombs.c:34)
==13750==    by 0x6BA76C: wchar2char (pg_locale.c:1641)
==13750==    by 0x653A7C: str_tolower (formatting.c:1591)

and various other related issues. I'm not sure if there's a legitimate
formatting.c issue or whether it's glibc changes around string handling
triggering spurious blurbs.

Greetings,

Andres Freund

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.