topic Re: -t parameter - tile size ? in Data Management Questions

-t parameter - tile size ?

davidsponka — Fri, 21 May 2010 06:03:32 GMT

hi,
i use sdegroup.exe utility and i would like to group features by tile size. default is 2. but 2 of what ? it is in miles or what ? i have an area which has about 30x25 kilometers, what tile size have i to choose normaly ? i have chosen 1 and it works 16 hours and still works.
thank you for advice and sorry for my english.

david

Re: -t parameter - tile size ?

VinceAngelo — Fri, 21 May 2010 10:42:46 GMT

It depends on what your map units are. If the data is degrees, then the default is two degrees.
If the data is feet, the default is two feet. If your data is in meters, it would be unwise to grid
at one meter (you might want to file a bug report on that, since the utility would have to expect
to generate 750 *million* grid cells, and over 32k or so is too many). Frankly, the only sensible
default value would be the grid size of first level spatial index (gsize0).

- V

Re: -t parameter - tile size ?

VinceAngelo — Fri, 21 May 2010 13:54:05 GMT

BTW: If you assume that each spatial query takes only 200 milliseconds, 750M queries
will run 150M seconds (~41666 hours or ~1736 days or ~4.75 years) -- Even if each
query is only 20ms, you probably don't want to try to let that job run to completion.

This reminds me that I need to add a progress meter on my spatial fragmentation
calculation tool (very verbose option, or verbose with >32k cells).

- V