So, feel free whether to go deeper continuing this discussion
Specifically:
WITH v_normalized AS (SELECT split_part(description, ' ', 25) AS type1, EXTRACT(MONTH FROM creation_date) AS month FROM qt_vehicle_ti)
SELECT type1, count(*) as count_total, count(*) filter (where month=10) AS count_m10 FROM v_normalized GROUP BY type1;
There is no benefit to having a join here.
Using WITH to compute v_normalized in just this query works but I suspect you will find you are writing something like that a lot which suggests it, or rather something similar but a bit more general, should be computed using CREATE VIEW.
