Horton

Re: [18] Policy on IMMUTABLE functions and Unicode updates

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Jeremy Schneider <schneider@ardentperf.com>
Cc: Daniel Verite <daniel@manitou-mail.org>, Jeff Davis <pgsql@j-davis.com>, Laurenz Albe <laurenz.albe@cybertec.at>, Noah Misch <noah@leadboat.com>, Peter Eisentraut <peter@eisentraut.org>, Tom Lane <tgl@sss.pgh.pa.us>, pgsql-hackers@postgresql.org
Date: 2024-07-24T19:47:12Z
Lists: 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 people did 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