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

[Nicklas Avén]

Then i gives the right answer.

/Nicklas


Sent from my Cat® phone.

Den 24 maj 2015 01:57 skrev Paul Ramsey <pramsey at cleverelephant.ca>:
>
> What happens when you run the query using the suspect house as a literal instead of doing the fun lateral query? 
>
> P.  
>
>
> --  
> http://postgis.net  
> http://cleverelephant.ca 
>
>
> On May 23, 2015 at 1:36:55 PM, Nicklas Avén (nicklas.aven at jordogskog.no) 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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>
>