Using a set returning function

A set returning function (also known as a table function) can be used in most places where a table, view, or subquery can be used. They are a powerful and flexible way to return data.

You can call the function in the SELECT clause, as you do with a scalar function:

postgres=# SELECT fibonacci_seq(3);
 fibonacci_seq 
---------------
      0
      1
      1
(3 rows)

You can also call the function as part of the FROM clause:

postgres=# SELECT * FROM fibonacci_seq(3);
 fibonacci_seq 
---------------
      0
      1
      1
(3 rows)

You can even call the function in the WHERE clause:

postgres=# SELECT * FROM fibonacci_seq(3) WHERE 1 = ANY(SELECT fibonacci_seq(3));
 fibonacci_seq 
---------------
      0
      1
      1
(3 rows)

You can limit the result set, just as in the case of querying a table:

postgres=# SELECT * FROM fibonacci_seq(10) as fib WHERE fib > 3;
 fibonacci_seq 
---------------
      5
      8
      13
      21
      34
(5 rows)

Using database-side functions...