[GRASS-dev] vector libs: file based spatial index

[Markus Metz]

Moritz Lennert wrote:
>
> Some testing:
[...]
>
>
> 3) erm_roads: 1883345 lines, 1883345 primitives
>
> time v.build erm_roads
>
> GRASS6.4:
> real    1m54.298s
> user    1m49.107s
> sys    0m2.888s
>
> GRASS7:
> real    2m54.266s
> user    2m40.606s
> sys    0m6.688s
>
> (Note the fact that here GRASS6.4 is significantly faster !)
Hmm yes I noticed that too. v.build in grass70 is sometimes slower,
sometimes faster, sometimes very similar to v.build in grass64. What is
really weird that this is true only on one of my two test systems, the
other one is always at least as fast, often faster than grass64. This
would be Linux 32 vs. Linux 64, both are Fedora 8. On Linux 64, grass70
is at least as fast as grass64, on Linux 32 grass70 v.build is sometimes
slower, sometimes faster than grass64 v.build.

I have a few handles on the speed of the spatial index and can make the
speed of v.build in grass70 very similar to grass64. Both the gain and
the loss would disappear. This only applies to v.build, v.what doesn't
show this weird behaviour and is to my dismay very robust against
tweaking the new spatial index, different settings give near identical
speed results.

Markus M