[gdal-dev] Re: OGR Select Features by Location...

[Joe Healy]

We're probably getting a little off topic, but

estrada.adam at gmail.com wrote:
> All,
>     How important is it to create the index for the intersection
> function I am trying to perform. 
It depends on how many of your points are within the bounding box of 
each polygon.
If the bounding box will reduce the number of point in polygon 
comparisons significantly then it is essential, otherwise a linear scan 
may be quicker if they are all inside.
>  We are talking over 15 million LIDAR
> points already loaded in to my PostgreSQL DB for a single dataset.  I
> read something that said that each set of 1 million points takes an
> hour to process when creating the index.
For sets with approx 8 million points someone here ran yesterday, the 
complete loading, indexing and querying took approximately 40 minutes 
per set.
Make sure you are using copy to insert the data. Email either the 
posgresql performance list or postgis list for other performance hints 
if it is still not quick enough.

Hope that helps,

Joe