Say, I wish to have a function returning a record, taking a row as parameter. However, from a performance perspective, I wish to be able to perform this query only on a subset by using a WHERE-clause.
I can only think of the following approach:
WITH ss AS ( SELECT * FROM my_table) SELECT * FROM my_function(ss) WHERE ss.field1 > 100
Question is: does the optimizer apply this WHERE-clause to the WITH-SELECT (resulting in "ss")?