SQLite Forum

Make overloaded "LIKE" function use INDEX
> LIKE search can not make use of indexes if one overrides the
> default like-function

That is correct.  If you override the built-in LIKE function, the
SQLite query optimizer has no way of knowing what semantics apply
to your new LIKE, and whether or not any of the optimizations it might
apply are valid.  No optimizations would be safe in the general case,
and so none are attempted.