Re: FETCH FIRST clause WITH TIES option

Alvaro Herrera <alvherre@2ndquadrant.com> writes:
> create table w (a point);

> # select * from w order by a fetch first 2 rows with ties;
> ERROR:  could not identify an ordering operator for type point
> LINE 1: select * from w order by a fetch first 2 rows with ties;
>                                   ^
> HINT:  Use an explicit ordering operator or modify the query.

> I'm not sure that the HINT is useful here.

That's not new to this patch, HEAD does the same:

regression=# create table w (a point);
CREATE TABLE
regression=# select * from w order by a ;
ERROR:  could not identify an ordering operator for type point
LINE 1: select * from w order by a ;
                                 ^
HINT:  Use an explicit ordering operator or modify the query.

It is a meaningful hint IMO, since (in theory) you could add
something like "USING <<" to the ORDER BY to specify a
particular ordering operator.  The fact that no suitable
operator is actually available in core doesn't seem like
a reason not to give the hint.

            regards, tom lane