SQLite - WHERE Clause & UDFs

Question

Intro

I have the following SQLite table with 198,305 geocoded portuguese postal codes:

CREATE TABLE "pt_postal" (
  "code" text NOT N         


        

Answer 1

I cannot tell from the documentation whether or not sqliteCreateFunction defines an aggregate, like SUM, or a scalar, like sqrt. Aggregate functions cannot be referenced in a WHERE clause; HAVING is required.

Per the SQLite UDF documentation, you need to know if only xFunc is populated, or if xStep and xFinal are. Those are the pointers SQLite uses to know the kind of function you're defining, and thus whether or not to honor it in a WHERE clause.