[postgis-devel] Wrong answer from new knn with recheck

[Nicklas Avén]

one more info

You have to create the indexes to reproduce the problem

without index it behaves as expected

Thanks
Nicklas


On Sat, 2015-05-23 at 22:36 +0200, Nicklas Avén wrote:
> Since I cannot reach trac I post it here.
> 
> I have been playing some with latest trunk and latest postgresql.
> 
> Since I cannot reach trac I cannot check that it is absolute latest
> trunk but I have r13544
> 
> PostgreSQL I pulled from git yesterday.
> 
> I have 2 data sets. one with roads and one with houses.
> 
> Attached is data that reproduces the problem.
> 
> table r is the roads and table t is the houses.
> 
> 
> If I then run this query:
> 
> SELECT t.navn, r.gid, st_distance(r.geom, t.geom) 
> FROM t CROSS JOIN LATERAL
> (SELECT r.gid, r.geom FROM r ORDER BY t.geom <->r.geom LIMIT 2) r;
> 
> I get this result:
>                navn               |   gid   |   st_distance    
> ----------------------------------+---------+------------------
>  Gramstad                         |  988075 | 90.2225986190226
>  Gramstad                         |  986169 | 128.356279805393
>  Sidhusgohpi                      |  982379 | 1379790.96016902
>  Sidhusgohpi                      | 1724598 |  27839.424840718
> 
> 
> What is totally wrong here is the third row. That road is 1379 km away.
> The last row gives the right answer. The closest road to that house is
> 27 km away.
> 
> With the full data sets I can play with the limit and see how roads from
> the first house in some way is following to the second house. road nr
> 982379 is just 215 meters away from house nr 1. So something is not
> letting go.
> 
> 
> Thanks
> 
> Nicklas Avén
> 
> 
> 
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