Este fragmento de código del autor de SQLAlchemy en este hilo de correo electrónico podría ser de ayuda
q1 = s.query(distinct(Appl.refid), Appl).\
filter(Appl.lastname.ilike('Williamson%')).\
filter(Appl.firstname.ilike('d%')).\
group_by(Appl).\
order_by(Appl.refid, Appl.appldate.desc())
q1 = q1.cte('distinct_query')
q2 = s.query(q1).order_by(q1.c.lastname, q1.c.firstname)
q2.all()
salidas como:
WITH distinct_query AS
(SELECT DISTINCT appl.refid AS anon_1, appl.id AS id, appl.firstname AS firstname, appl.lastname AS lastname, appl.refid AS refid, appl.appldate AS appldate
FROM appl
WHERE appl.lastname ILIKE %(lastname_1)s AND appl.firstname ILIKE %(firstname_1)s GROUP BY appl.id, appl.firstname, appl.lastname, appl.refid, appl.appldate ORDER BY appl.refid, appl.appldate DESC)
SELECT distinct_query.anon_1 AS distinct_query_anon_1, distinct_query.id AS distinct_query_id, distinct_query.firstname AS distinct_query_firstname, distinct_query.lastname AS distinct_query_lastname, distinct_query.refid AS distinct_query_refid, distinct_query.appldate AS distinct_query_appldate
FROM distinct_query ORDER BY distinct_query.lastname, distinct_query.firstname