[postgis-devel] knn test - first result

[maplabs at light42.com]

>
> I can't see how knn would help st_dwithin. The thing with knn is that
> the index returns the result in order..... 

ok, I am starting to understand this a little bit more.. 
yes, I picked a bad example.. too hasty, as usual... 

>
> BTW, have you patched PostGIS 1.4 to compile it against PostgreSQL 9.1?
> I ask because ticket 940 http://trac.osgeo.org/postgis/ticket/940# 
> should make it impossible otherwise if Paul didn't fix 1.4 too. 
>

 misunderstanding there.. maybe this following one is formatted more clearly

Is this a better test? 
---------------------
KNN Tester #2
--------------------

explain analyze select name, geonameid from us_locations
  where 
st_distance(thepoint_lonlat,st_geomfromEWKT('SRID=4326;POINT(-86.6296824 
31.2590605)') ) < 0.01;

=============================================================================================
aced    2 core amd
 PostgreSQL 8.4.7 on x86_64-pc-linux-gnu, compiled by GCC gcc-4.4.real 
(Debian 4.4.5-8) 4.4.5, 64-bit
 POSTGIS="1.4.1SVN" GEOS="3.3.0-CAPI-1.7.0" PROJ="Rel. 4.7.1, 23 
September 2009" USE_STATS

 Seq Scan on us_locations  (cost=0.00..73458.36 rows=628741 width=26) 
(actual time=0.129..2847.318 rows=2 loops=1)
   Filter: (st_distance(thepoint_lonlat, 
'0101000020E610000079B768B74CA855C0772FF7C951423F40'::geometry) < 
0.01::double precision)
 Total runtime: 2847.457 ms

=============================================================================================
xps    4 core intel
 PostgreSQL 9.0.3 on x86_64-pc-linux-gnu, compiled by GCC gcc-4.4.real 
(Ubuntu/Linaro 4.4.4-14ubuntu5) 4.4.5, 64-bit
 POSTGIS="1.5.3SVN" GEOS="3.3.0-CAPI-1.7.0" PROJ="Rel. 4.7.1, 23 
September 2009" LIBXML="2.7.7" USE_STATS
  
 Seq Scan on us_locations  (cost=0.00..540426.01 rows=628900 
width=26) (actual time=0.019..1692.868 rows=2 loops=1)
   Filter: (st_distance(thepoint_lonlat, 
'0101000020E610000079B768B74CA855C0772FF7C951423F40'::geometry) < 
0.01::double precision)
 Total runtime: 1692.888 ms

=============================================================================================
devel  2-core virtual machine on xps
 PostgreSQL 9.1beta1 on i686-pc-linux-gnu, compiled by GCC gcc (Debian 
4.4.5-8) 4.4.5, 32-bit
 POSTGIS="2.0.0SVN" GEOS="3.3.0rc1-CAPI-1.7.0" PROJ="Rel. 4.7.1, 23 
September 2009" LIBXML="2.7.8" USE_STATS
 
  Seq Scan on us_locations  (cost=0.00..538275.26 rows=628694 
width=26) (actual time=0.102..3001.324 rows=2 loops=1)
   Filter: (st_distance(thepoint_lonlat, 
'0101000020E610000079B768B74CA855C0772FF7C951423F40'::geometry) < 
0.01::double precision)
 Total runtime: 3001.547 ms
 
 

>