[mapserver-users] Oracle Spatial

[Stuart.Harlan at modot.mo.gov]

I am querying an Oracle Spatial table.  I am restricting the query using 
an attribute in the table (road type).  In examining the query sent to 
Oracle, it seems to query by attribute first, then by spatial envelope. 
For datasets that only return a few features in the attribute query, this 
seems fairly efficient.  However, for datasets that return many features 
in the attribute query that lie over a large spatial area, it would seem 
more efficient to limit by spatial envelope first, then by attributes, 
especially if the query area is relatively small compared to the spatial 
extent of the dataset.  Can the user be allowed to set the 
spatial/attribute query order?

Example query - attribute query is executed first, then spatial.  For 
small spatial areas, the query might be faster if the spatial filter were 
executed first.

DATA "SHAPE FROM (SELECT SHAPE FROM ROAD_TABLE WHERE DESG IN 
('CST','CRD')) USING SRID 8307"

Stuart Harlan
Senior Information Systems Technologist
GIS Web Services
Transportation Planning Division
Missouri Department of Transportation
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