Date: Mon, 29 Jun 2026 18:29:19 -0700
From: Noah Misch <noah@leadboat.com>
To: Jeff Davis <pgsql@j-davis.com>
Cc: Andreas Karlsson <andreas@proxel.se>, pgsql-hackers@postgresql.org,
	Peter Eisentraut <peter@eisentraut.org>
Subject: Re: Collation & ctype method table, and extension hooks
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On Wed, Jun 11, 2025 at 10:49:17PM -0700, Jeff Davis wrote:
> Attached v16.

> I plan to commit this soon after branching.

> Subject: [PATCH v16 1/4] Control ctype behavior internally with a method
>  table.
> 
> Previously, pattern matching and case mapping behavior branched based
> on the provider.
> 
> Refactor to use a method table, which is less error-prone and easier
> to hook.

This became refactor commit 5a38104.  In a UTF8 database, the commit changed
the behavior of:

  SELECT 'café' ILIKE 'caf_' COLLATE "C";

That query reports true in v18, false in v19.  I've copied Claude's whole
review for the commit to
https://docs.google.com/document/d/19_xKpKUQlY5N51qbfXyipXs3rqIYEC3qk5oaUDJ48YA/edit?tab=t.0.
Two of its other findings sound potentially important, but I didn't verify
them.

nm