Postgres 15

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Help with an interesting Postgres question: Why isn't an Index Only Scan used on a partition accessed via the parent table?.

CREATE OR REPLACE FUNCTION f_fibonacci (pstop int = 10)
  RETURNS SETOF int
  LANGUAGE plpgsql IMMUTABLE STRICT AS
$func$
DECLARE
    a int := 0;
    b int := 1;
BEGIN
   RETURN NEXT 0;
   RETURN NEXT 1;
   LOOP
      a := a + b;
      EXIT WHEN a >= pstop;
      RETURN NEXT a;

      b := b + a;
      EXIT WHEN b >= pstop;
      RETURN NEXT b;
   END LOOP;
END;
$func$;

CREATE FUNCTION

SELECT * FROM f_fibonacci();

f_fibonacci

0

1

1

2

3

5

8

SELECT 7

SELECT * FROM f_fibonacci(20);

f_fibonacci

0

1

1

2

3

5

8

13

SELECT 8