Postgres 16

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 t (
    a VARCHAR(10) COLLATE "C.utf8"
    NOT NULL
    DEFAULT 'abc'
);

CREATE TABLE


SELECT 
    table_name, column_name, is_nullable, column_default,
    character_maximum_length, collation_name
FROM 
    information_schema.columns cols
WHERE 
    table_name = 't'; 


table_name
column_name
is_nullable
column_default
character_maximum_length
collation_name


t
a
NO
'abc'::character varying
10
C.utf8



SELECT 1


ALTER TABLE t ALTER COLUMN a TYPE VARCHAR(20);

ALTER TABLE


SELECT --observe nothing changed except the max len, as we wanted
    table_name, column_name, is_nullable, column_default,
    character_maximum_length, collation_name
FROM 
    information_schema.columns cols
WHERE 
    table_name = 't';  


table_name
column_name
is_nullable
column_default
character_maximum_length
collation_name


t
a
NO
'abc'::character varying
20
null



SELECT 1