Re: [18] Policy on IMMUTABLE functions and Unicode updates - Mailing list pgsql-hackers

On Wed, Jul 24, 2024 at 3:43 PM Jeremy Schneider
<schneider@ardentperf.com> wrote:
> But non-unique indexes for case insensitive searches will be more common. Historically this is the most common way
peopledid case insensitive on oracle. 
>
> Changing ctype would mean these queries can return wrong results

Yeah. I mentioned earlier that I very recently saw a customer query
with UPPER() in the join condition. If someone is doing foo JOIN bar
ON upper(foo.x) = upper(bar.x), it is not unlikely that one or both of
those expressions are indexed. Not guaranteed, of course, but very
plausible.

--
Robert Haas
EDB: http://www.enterprisedb.com