Re: application of KNN code to US zipcode searches?

Tom Lane <tgl@sss.pgh.pa.us>

From: Tom Lane <tgl@sss.pgh.pa.us>
To: Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
Cc: Mark Stosberg <mark@summersault.com>, pgsql-performance@postgresql.org
Date: 2011-02-17T19:13:05Z
Lists: pgsql-performance
Heikki Linnakangas <heikki.linnakangas@enterprisedb.com> writes:
> The existing opclasses only support distance-to-a-point, but I believe 
> the KNN gist code is flexible enough that it could be used for distance 
> to the edge of a shape as well. Someone just needs to write the 
> operators and support functions.

The distance has to be exactly computable from the index entry, so you'd
need to store the whole shape in the index, not just a bounding box.
Not sure how practical that will be for complex shapes.

			regards, tom lane