[mapserver-users] SDE performance and error

[Frank Warmerdam]

> The result after shptree using default parameters was great.  I can now get
> rid of the 2 files and use vdotrd.
> 
> If I get the time to benchmark against SDE I will let you know.  I'm
> installing Oracle 8.1.7 and SDE 8.1 as we speak on a SUN E4500 (8 400mhz
> CPUs, 8 mb ECache each CPU and 4 GB RAM). This should be a nice test.

Lowel,

Sweet machine!

> I assume you wrote this index?  It's based on R-tree or Quad-tree type
> algorithms as opposed to ESRI's indexing scheme?

The algorithm is a simple quad tree.  The only clever aspect is that I
general a moderate overlap between quads to ensure that small objects that
overlap a quad boundary don't necessarily get promoted too far up the quad
tree.  

I haven't checked how Steve has done the quadtrees on disk, but in an 
ideal world only portions of the index file that are required would be
read.  Otherwise you end up consuming at least something like 4 or 8 bytes
of memory for every shape just to hold the index.  However, this would be 
OK for medium sized files. 

Best regards,

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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent