ERROR: could not identify an equality operator for type box

Ok, casting to ::text solves the problem, but still I think we
need to fix it in the right way

Oleg
On Sat, 4 Dec 2010, Oleg Bartunov wrote:

Hi there,

create table qq (b box);
CREATE TABLE
select count(*), b from qq group by b;
ERROR: could not identify an equality operator for type box
LINE 1: select count(*), b from qq group by b;

but following select works fine

select ' (43.6038,48.8664536),(1.3620777,1.44327)'::box = '
(43.6038,48.8664536),(1.3620777,1.44327)'::box;
?column? ----------
t
(1 row)
^
What does it means ?

Regards,
Oleg
_____________________________________________________________
Oleg Bartunov, Research Scientist, Head of AstroNet (www.astronet.ru),
Sternberg Astronomical Institute, Moscow University, Russia
Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
phone: +007(495)939-16-83, +007(495)939-23-83

Regards,
Oleg
_____________________________________________________________
Oleg Bartunov, Research Scientist, Head of AstroNet (www.astronet.ru),
Sternberg Astronomical Institute, Moscow University, Russia
Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
phone: +007(495)939-16-83, +007(495)939-23-83

On 03.12.2010 23:53, Oleg Bartunov wrote:

create table qq (b box);
CREATE TABLE
select count(*), b from qq group by b;
ERROR: could not identify an equality operator for type box
LINE 1: select count(*), b from qq group by b;

but following select works fine

select ' (43.6038,48.8664536),(1.3620777,1.44327)'::box = '
(43.6038,48.8664536),(1.3620777,1.44327)'::box;
?column? ----------
t
(1 row)
^
What does it means ?

GROUP BY requires b-tree sort operators. Although there is a '='
operator for box, there is no b-tree opclass.

--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com

Heikki Linnakangas <heikki.linnakangas@enterprisedb.com> writes:

On 03.12.2010 23:53, Oleg Bartunov wrote:

create table qq (b box);
CREATE TABLE
select count(*), b from qq group by b;
ERROR: could not identify an equality operator for type box
What does it means ?

GROUP BY requires b-tree sort operators. Although there is a '='
operator for box, there is no b-tree opclass.

A hash opclass would do too, as of recent releases ... but box hasn't
got one of those either.

There are some semantic issues involved here, notably that box_eq is
actually equality-of-areas, and that both it and box_same use fuzzy
equality which does not work well with either hash or sort-based
semantics. So you'd need to look at redefining the operator behavior
before you could get far.

regards, tom lane