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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 cast_to(_js jsonb, INOUT _target_type anyelement = NULL::text)
LANGUAGE plpgsql PARALLEL SAFE AS
$func$
BEGIN
SELECT _js ->> pg_typeof(_target_type)::text
INTO _target_type;
END
$func$;
CREATE FUNCTION
-- test table
CREATE TABLE tbl (id int, js jsonb);
INSERT INTO tbl VALUES
(1, '{"int":66, "integer":"42", "text":"abc", "date":"2019-12-12"}')
, (2, '{"point":"(1,2)"}')
;
CREATE TABLE
INSERT 0 2
SELECT *
, cast_to(js, NULL::int ) AS my_int
, cast_to(js, NULL::text ) AS my_text
, cast_to(js, NULL::date ) AS my_date
, cast_to(js, NULL::point) AS my_point
, cast_to(js ) AS my_default -- no 2nd param
FROM tbl;
| id | js | my_int | my_text | my_date | my_point | my_default |
|---|---|---|---|---|---|---|
| 1 | {"int": 66, "date": "2019-12-12", "text": "abc", "integer": "42"} | 42 | abc | 2019-12-12 | null | abc |
| 2 | {"point": "(1,2)"} | null | null | null | (1,2) | null |
SELECT 2