Horton

Re: Add support for AT LOCAL

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

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Noah Misch <noah@leadboat.com>
Cc: Thomas Munro <thomas.munro@gmail.com>, Michael Paquier <michael@paquier.xyz>, Vik Fearing <vik@postgresfriends.org>, cary huang <hcary328@gmail.com>, pgsql-hackers@lists.postgresql.org
Date: 2023-10-17T05:40:18Z
Lists: pgsql-hackers 
Noah Misch <noah@leadboat.com> writes:
> On Mon, Oct 16, 2023 at 01:54:23AM -0400, Tom Lane wrote:
>> Ugh.  So if the failure is robust enough to persist across
>> several major xlc versions, why couldn't Thomas reproduce it?

> Beats me.  hornet wipes its starting environment down to OBJECT_MODE=32_64
> PERL5LIB=/home/nm/sw/cpan64/lib/perl5 SPECIES=xlc64 PATH=/usr/bin, then
> applies all the environment settings seen in buildfarm logs.

I was able to reproduce the failure on cfarm111 after adopting
these settings from hornet's configuration:

export OBJECT_MODE=64
export CC='xlc_r -D_LARGE_FILES=1 '
export CFLAGS='-O2 -qmaxmem=33554432 -qsuppress=1500-010:1506-995 -qsuppress=1506-010:1506-416:1506-450:1506-480:1506-481:1506-492:1506-944:1506-1264 -qinfo=all:nocnd:noeff:noext:nogot:noini:noord:nopar:noppc:norea:nouni:nouse -qsuppress=1506-374:1506-419:1506-434:1506-438:1506-451:1506-452:1506-453:1506-495:1506-786'

and doing

./configure --enable-cassert --enable-debug --without-icu --prefix=/home/tgl/testversion

etc etc.

It is absolutely, gold-platedly, a compiler bug, because inserting
a debug printf into the loop

	while (result->time >= USECS_PER_DAY)
		result->time -= USECS_PER_DAY;

makes the failure go away.  Unfortunately, I've not yet found another
way to make it go away :-(.  My upthread idea of using a local variable
instead of result->time is no help, and some other random code
alterations didn't change the results either.

Not sure where we go from here.  While I don't have much hesitation
about blowing off xlc_r 12.1, it would be sad if their latest
toolchain doesn't work either.  (I didn't try permuting the code
while using the newer compiler, though.)

			regards, tom lane

Commits

  1. Dodge a compiler bug affecting timetz_zone/timetz_izone.

  2. Back-patch test cases for timetz_zone/timetz_izone.

  3. Add regression test coverage for timetz_izone().

  4. Add support for AT LOCAL

  5. doc: Mention timezone(zone, time) in section for AT TIME ZONE

  6. Use HASH_BLOBS for xidhash.