Horton

Re: pg_trgm comparison bug on cross-architecture replication due to different char implementation

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

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Masahiko Sawada <sawada.mshk@gmail.com>
Cc: Noah Misch <noah@leadboat.com>, Joe Conway <mail@joeconway.com>, Peter Eisentraut <peter@eisentraut.org>, Alexander Korotkov <aekorotkov@gmail.com>, "Guo, Adam" <adamguo@amazon.com>, "pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>, Nathan Bossart <nathandbossart@gmail.com>, Jim Mlodgenski <jimmy76@gmail.com>
Date: 2024-09-10T21:56:47Z
Lists: pgsql-hackers 
Masahiko Sawada <sawada.mshk@gmail.com> writes:
> On Tue, Sep 10, 2024 at 11:57 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> Yeah, that seems like it could work.  But are we sure that replicas
>> get a copy of the primary's control file rather than creating their
>> own?

> Yes, I think so. Since at least the system identifiers of primary and
> replicas must be identical for physical replication, if replicas use
> their own control files then they cannot start the replication.

Got it.  So now I'm wondering if we need all the complexity of storing
stuff in the GIN metapages.  Could we simply read the (primary's)
signedness out of pg_control and use that?  We might need some caching
mechanism to make that cheap enough, but accessing the current index's
metapage is far from free either.

			regards, tom lane

Commits

  1. pg_upgrade: Check for the expected error message in TAP tests.

  2. Fix a typo in 005_char_signedness.pl test.

  3. Add test 005_char_signedness.pl to meson.build.

  4. Fix an issue with index scan using pg_trgm due to char signedness on different architectures.

  5. pg_upgrade: Add --set-char-signedness to set the default char signedness of new cluster.

  6. pg_upgrade: Preserve default char signedness value from old cluster.

  7. pg_resetwal: Add --char-signedness option to change the default char signedness.

  8. Add default_char_signedness field to ControlFileData.

  9. Remove unneeded nbtree array preprocessing assert.