Usé un enfoque un poco diferente:
# the first subquery, select all ids from SOME_TABLE where some_field is not NULL
s1 = select([SOME_TABLE.c.id]).where(SOME_TABLE.c.some_field != None)
# the second subquery, select all ids from SOME_TABLE where some_field is NULL
s2 = select([SOME_TABLE.c.id]).where(SOME_TABLE.c.some_field != None)
# union s1 and s2 subqueries together and alias the result as "alias_name"
q = s1.union(s2).alias('alias_name')
# run the query and limit the aliased result to 10
session.query(q).limit(10)
Aquí está el sql producido:
SELECT alias_name.id AS alias_name_id
FROM (SELECT some_table.id AS id
FROM some_table
WHERE some_table.some_field IS NOT NULL UNION SELECT some_table.id AS id
FROM some_table
WHERE some_table.some_field IS NULL) AS alias_name
LIMIT 10
Creo que este es el resultado que querías.
