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Re: point types in "DISTINCT" queries

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On Jun 29, 2011, at 10:25 AM, Magnus Hagander <magnus@xxxxxxxxxxxx> wrote:

On Wed, Jun 29, 2011 at 06:53, Jeff Davis <pgsql@xxxxxxxxxxx> wrote:
On Tue, 2011-06-28 at 18:56 -0400, Jonathan S. Katz wrote:

I looked into the mailing list archives and found a potential answer
on this thread:
http://archives.postgresql.org/pgsql-general/2009-10/msg01122.php
However I wanted to see if it was still necessary that I would need
the complete btree operator class to run such a query.

Yes, the default btree operator class is used to find the equality
operator. Even though you have defined the operator "=", postgresql
doesn't rely on that meaning "equals" -- the btree operator class is
what imparts that meaning.

Are there plans to have a defined "=" operator on the point type?  I
can understand how the other geometric types, "=" would represent
area, but AFAIK I think "=" could be safely applied on a point type
(and i realize I could submit a patch for that :-) maybe depending on
the resolution to this / refreshing my C...).

The built-in geometric types haven't received a lot of attention lately. Most people who use geometric data use the PostGIS extension, which is a sophisticated extension that can deal with that kind of data. You might
want to check that out and see if it meets your needs.

Perhaps someone is interested in bringing the built-in geometric types up to speed; but I think most of the interest is moving things like this
out to extensions where they can be more easily be maintained by
interested parties.

Given that they are the only ones supporting knn-gist, I would expect
them to actually become *more* popular with 9.1 - at least until such
time as postgis adds support for it...

In fact that is my use-case - I will be performing nearest-neighbor lookups (and will be running 9.1b2 on this data set shortly). However, because most of the geospatial work is relatively straightforward, I didn't want to use PostGIS for this application. But that might change in the near future depending on the requirements.

But for now tasks like ensuing uniqueness amongst points are slightly more difficult. My current solution is breaking out the (x,y) coords into different columns

Jonathan

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