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

This query (provided by @OMGPonies):

SELECT *
    FROM (
        SELECT
            "code",
            geo(38.73311, -9.138707, "geo_latitude", "geo_longitude") AS "distance"
            FROM "pt_postal" WHERE 1 = 1
                AND "geo_latitude" BETWEEN 38.7241268076 AND 38.7420931924
                AND "geo_longitude" BETWEEN -9.15022289523 AND -9.12719110477
    )
        WHERE "distance" <= 1
    ORDER BY "distance" ASC
LIMIT 2048;

Correctly returns the 873 records, ordered by distance in ~0.07 seconds.

However, I'm still wondering why SQLite doesn't evaluate geo() in the WHERE clause, like MySQL...