On Tue, 2025-09-09 at 23:13 -0400, Jonathan S. Katz wrote:
> Hi,
>
> Attached is a draft of the PostgreSQL 18 GA press release. A few
> comments before the ask for reviewing:
"This release adds the [`PG_UNICODE_FAST`], which accelerates lookups
using the `upper` and `lower` string comparison functions, and helps
speed up the new [`casefold`] function for case-insensitive
comparisons."
Use the link:
https://www.postgresql.org/docs/18/collation.html#COLLATION-MANAGING-STANDARD
which is a bit more descriptive. (Though perhaps that document could be
improved with examples.)
What's actually new with PG_UNICODE_FAST are the "full" Unicode
semantics for case transformations, e.g. it uppercases 'ß' to 'SS'. The
rest is the same as PC_C_UTF8, which uses "simple" Unicode semantics.
The name PG_UNICODE_FAST is meant to convey that it provides full
unicode semantics for case mapping and pattern matching, while also
being fast because it uses memcmp for comparisons. While the name
PG_C_UTF8 is meant to convey that it's closer to what users of the libc
"C.UTF-8" locale might expect.
Regards,
Jeff Davis
