[DAS2] range searches

[Andrew Dalke]

I think Gregg has thought the most about this one.

We have 4 classes of range search:

'inside' (feature completely inside request range)
'overlaps' (feature overlaps the request range)
'contains' (feature completely contains request range)
'identical' (feature is exactly the request range)

They exist for smart clients which want to limit the
region request size based on previously fetched knowledge.

Example: client is viewing "500:600" and zooms out to
"400:700".  In that case the client could ask for
features which
   overlap 400:500 OR overlap 600:700
   excluding those which overlap 500:600.

If that's the case, the selection language isn't powerful
enough.  There's no way to choose "excluding".

The other option is to issue only the overlap queries.

Does the query language need to be more powerful to
allow "excluding what I know about these regions" for
people like Gregg?

Another question came up; are queries like

   overlap 400:500 OR inside 900:1000

useful?  I don't think so.  If it is, it is not supported
by the current language which only does AND of dissimilar
terms.


					Andrew
					dalke at dalkescientific.com