Re: sorting a union over inheritance vs pathkeys

Michael Glaesemann <grzm@seespotcode.net> writes:
> I’ve come across an issue when creating a union over tables which includes inheritance:
> CREATE TABLE events (event_id INT NOT NULL);
> -- CREATE TABLE
> CREATE UNIQUE INDEX events_event_id_key ON events (event_id);
> -- CREATE INDEX

> CREATE TABLE legacy_events (event_id INT NOT NULL);
> -- CREATE TABLE
> CREATE UNIQUE INDEX legacy_events_event_id_key ON legacy_events (event_id);
> -- CREATE INDEX

> CREATE TABLE events_2 () INHERITS (events);
> -- CREATE TABLE
> -- this index isn't necessary to reproduce the error
> CREATE UNIQUE INDEX events_2_event_id_key ON events_2 (event_id);
> -- CREATE INDEX

> SELECT event_id
>  FROM (SELECT event_id
>          FROM events
>        UNION ALL
>        SELECT event_id
>          FROM legacy_events) _
>  ORDER BY event_id;
> -- ERROR:  could not find pathkey item to sort

Hm ... I can reproduce that in 9.3 but it seems fine in 9.4 and HEAD.
Don't know what's going on exactly.
        regards, tom lane