title: postgres spatial indexing
body: <p>I can't seem to find much documentation on this.
  What's the simplest way to create a database/table on postgres supporting a query like this  SELECT * FROM table WHERE distance(POINT(0,0), table.location) &lt;= 1000m;
  Where POINT(0,0) and table.location should be latitude/longitude pair, and 1000m is 1000 meters. And how should I go about indexing that table?
  Thanks.</p>