Thread

Re: [SQL] can I index a field of type "point"?

selkovjr@mcs.anl.gov — 2000-01-24T02:24:48Z

> Hello!
> 
> 
> Is there a way to index a point field? The obvious method didn't work
> for me:
> mark=> create index lon_lat_idx on zip (lon_lat);
> ERROR:  Can't find a default operator class for type 600

It is true that there is no default opclass for point. As a matter of
fact, there is no opclass for defined for point at all. You can try
box_ops, though:

create table zip (lon_lat point);
insert into zip values('120,47');
insert into zip values('120,48');
insert into zip values('120,49');
insert into zip values('122,47');
insert into zip values('124,60');

create index lon_lat_idx on zip using rtree (lon_lat box_ops);

This seems to work:

test=> select * from zip where lon_lat ~= '120,47';
lon_lat 
--------
(120,47)
(1 row)

test=> select * from zip where lon_lat @ '120,45,125,49';
lon_lat 
--------
(120,47)
(120,46)
(2 rows)

However, you might want to check it out with a substantial data set
and verify that this index is actually used. If it isn't, I would
simply represent points as boxes.

--Gene