On 09.12.24 11:11, Peter Eisentraut wrote:
> lowerstr() and lowerstr_with_len() in ts_locale.c do the same thing as
> str_tolower(), except that the former don't use the common locale
> provider framework but instead use the global libc locale settings.
>
> This patch replaces uses of lowerstr*() with str_tolower(...,
> DEFAULT_COLLATION_OID). For instances that use a libc locale globally,
> this will result in exactly the same behavior. For instances that use
> other locale providers, you now get consistent behavior and are no
> longer dependent on the libc locale settings.
>
> Most uses of these functions are for processing dictionary and
> configuration files. In those cases, using the default collation seems
> appropriate. At least we don't have a more specific collation
> available. But the code in contrib/pg_trgm should really depend on the
> collation of the columns being processed. This is not done here, this
> can be done in a separate patch.
>
> (You can probably construct some edge cases where this change would
> create some locale-related upgrade incompatibility, for example if
> before you used a combination of ICU and a differently-behaving libc
> locale. We can document this in the release notes, but I don't think
> there is anything more we can do about this.)
There is a PG18 open item to document this possible upgrade incompatibility.
I think the following text could be added to the release notes:
"""
The locale implementation underlying full-text search was improved. It
now observes the locale provider configured for the database. It was
previously hardcoded to use the configured libc LC_CTYPE setting. In
database clusters that use a locale provider other than libc and where
the locale configured through that locale provider behaves differently
from the LC_CTYPE setting configured for the database, this could cause
changes in behavior of some functions related to full-text search as
well as the pg_trgm extension. When upgrading such database clusters
using pg_upgrade, it is recommended to reindex all indexes related to
full-text search and pg_trgm after the upgrade.
"""
The commit reference is fb1a18810f0.
Thoughts?
