Testing with https://ozh.org/temp/UPLOL-lowrolf.html :

✔️ case sensitive for URL

✔️ case sensitive for short URL

✔️ case insensitive for titles

I tweaked #3997 (comment) a bit so it accurately describes the behavior of titles. :)

Is it overkill to use COLLATE now that you replaced CONCAT_WS() with multiple `field` LIKE (:search) clauses? If tested individually, I would think that each column would naturally behave according to its set collation. For title + ip, that's already utf8mb4_unicode_ci, and utf8mb4_bin for url + keyword.

If we can accomplish the same thing with fewer conditionals, it's nicer—and probably more performant if we can avoid making the DB convert collations. (Not that I expect search to be a major performance issue, but… why make things slow just because? 😁)

With no COLLATE clause, it doesn't work :

        $where['sql'] .= " AND `keyword` LIKE (:search)
                        OR `url` LIKE (:search)
                        OR `title` LIKE (:search)
                        OR `ip` LIKE (:search) ";

Ah, fun. Guess we'll do it this way, indeed.