Re: pg_trgm comparison bug on cross-architecture replication due to different char implementation - Mailing list pgsql-hackers

From Tom Lane
Subject Re: pg_trgm comparison bug on cross-architecture replication due to different char implementation
Date
Msg-id 2042246.1727841462@sss.pgh.pa.us
Whole thread Raw
In response to Re: pg_trgm comparison bug on cross-architecture replication due to different char implementation  (Noah Misch <noah@leadboat.com>)
Responses Re: pg_trgm comparison bug on cross-architecture replication due to different char implementation
List pgsql-hackers
Noah Misch <noah@leadboat.com> writes:
> On Tue, Oct 01, 2024 at 11:55:48AM -0700, Masahiko Sawada wrote:
>> Considering that the population of database cluster signedness will
>> converge to signedness=true in the future, we can consider using
>> -fsigned-char to prevent similar problems for the future. We need to
>> think about possible side-effects as well, though.

> It's good to think about -fsigned-char.  While I find it tempting, several
> things would need to hold for us to benefit from it:

> - Every supported compiler has to offer it or an equivalent.
> - The non-compiler parts of every supported C implementation need to
>   cooperate.  For example, CHAR_MIN must change in response to the flag.  See
>   the first comment in cash_in().
> - Libraries we depend on can't do anything incompatible with it.

> Given that, I would lean toward not using -fsigned-char.  It's unlikely all
> three things will hold.  Even if they do, the benefit is not large.

I am very, very strongly against deciding that Postgres will only
support one setting of char signedness.  It's a step on the way to
hardware monoculture, and we know where that eventually leads.
(In other words, I categorically reject Sawada-san's assertion
that signed chars will become universal.  I'd reject the opposite
assertion as well.)

            regards, tom lane



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