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

Apart from two doc issues, this is ready:

On Tue, Feb 18, 2025 at 01:23:20PM -0800, Masahiko Sawada wrote:
> On Mon, Feb 17, 2025 at 2:57 PM Noah Misch <noah(at)leadboat(dot)com> wrote:
> > On Fri, Jan 17, 2025 at 05:11:41PM -0800, Masahiko Sawada wrote:

> + However, when upgrading from <productname>PostgreSQL</productname> 17 or,
> + earlier <application>pg_upgrade</application> adopts the char signedness

s/or, earlier/or earlier,/

> --- a/doc/src/sgml/ref/pg_resetwal.sgml
> +++ b/doc/src/sgml/ref/pg_resetwal.sgml
> @@ -171,6 +171,22 @@ PostgreSQL documentation
> </para>
>
> <variablelist>
> + <varlistentry>
> + <term><option>--char-signedness=<replaceable class="parameter">option</replaceable></option></term>
> + <listitem>
> + <para>
> + Manually set the default char signedness. Possible values are
> + <literal>signed</literal> and <literal>unsigned</literal>.
> + </para>
> + <para>
> + A safe value for this option is, if known, the default char signedness
> + of the platform where the database cluster was initialized. However,

Only if initialized on v17 or earlier. I recommend this edit:

diff --git a/doc/src/sgml/ref/pg_resetwal.sgml b/doc/src/sgml/ref/pg_resetwal.sgml
index a72678d..dd011d2 100644
--- a/doc/src/sgml/ref/pg_resetwal.sgml
+++ b/doc/src/sgml/ref/pg_resetwal.sgml
@@ -179,8 +179,11 @@ PostgreSQL documentation
<literal>signed</literal> and <literal>unsigned</literal>.
</para>
<para>
- A safe value for this option is, if known, the default char signedness
- of the platform where the database cluster was initialized. However,
+ For a database cluster that <command>pg_upgrade</command> upgraded from
+ a <productname>PostgreSQL</productname> version before 18, the safe
+ value would be the default <type>char</type> signedness of the platform
+ that ran the cluster before that upgrade. For all other
+ clusters, <literal>signed</literal> would be the safe value. However,
this option is exclusively for use with <command>pg_upgrade</command>
and should not normally be used manually.
</para>