[postgis-devel] CascadedUnion Early Results

[Mark Cave-Ayland]

Paul Ramsey wrote:

> For completeness, the whole table, about 4x faster:
> 
> uniontest=# select count(*) from counties;
>  count
> -------
>   3140
> (1 row)
> 
> uniontest=# select st_area(st_union(the_geom)) from counties;     st_area
> ------------------
>  1095.88034519544
> (1 row)
> 
> Time: 42352.399 ms
> 
> uniontest=# select st_area(st_union_fast(the_geom)) from counties;
>      st_area
> ------------------
>  1095.88034519544
> (1 row)
> 
> Time: 11493.832 ms

Fascinating. What would be really interesting would be to compare the 
times with the same dataset in JTS so we can get a feel as to whether 
there is any more overhead in the array_accum/GEOS conversion code.


ATB,

Mark.

-- 
Mark Cave-Ayland
Sirius Corporation - The Open Source Experts
http://www.siriusit.co.uk
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