Postgres 11

By using db<>fiddle, you agree to license everything you submit by Creative Commons CC0.

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

CREATE TABLE my_table (
    my_col text[]
);

INSERT INTO my_table VALUES
('{a,b}'),
('{c,d,e}');
2 rows affected

SELECT
    *
FROM
    my_table,
    unnest(my_col)


my_col
unnest


{a,b}
a

{a,b}
b

{c,d,e}
c

{c,d,e}
d

{c,d,e}
e


SELECT
    *
FROM
    my_table CROSS JOIN
    unnest(my_col)


my_col
unnest


{a,b}
a

{a,b}
b

{c,d,e}
c

{c,d,e}
d

{c,d,e}
e


SELECT
    *
FROM
    my_table CROSS JOIN LATERAL
    unnest(my_col)


my_col
unnest


{a,b}
a

{a,b}
b

{c,d,e}
c

{c,d,e}
d

{c,d,e}
e