[postgis-users] Quick note on how NOT to use ST_Intersects()

Chris Hermansen chris.hermansen at timberline.ca
Thu Sep 4 18:05:57 PDT 2008


Yo Dylan, thanks for trying that out for the rest of us :-)

Dylan Beaudette wrote:
> Hi,
>
> Thinking (falsely) that I would cleverly locate where two sets of polygons did 
> not overlap, I gave something like this a try:
>
> CREATE TABLE big_mistake as
> SELECT a.something, b.something
> FROM
> a
> JOIN
> b
> ON
> ST_Instersects(a,b) = FALSE;
>
> ... postgresql then proceeded to fill my harddrive with garbage!
>
> Note the self: don't try seemingly clever tricks without first *thinking* 
> about them.
>
> Dylan
>
>
>   


-- 
Regards,

Chris Hermansen         mailto:chris.hermansen at timberline.ca
tel+1.604.714.2878 · fax+1.604.733.0631 · mob+1.778.232.0644
Timberline Natural Resource Group · http://www.timberline.ca
401 · 958 West 8th Avenue  · Vancouver BC · Canada · V5Z 1E5




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