Query for Oracle SDO Data without using SDO_FILTER

Johann Nothbauer nothbauer at rmdata.at
Fri Nov 17 06:54:39 EST 2006


Is there any way to prevent Mapguide from using the SDO_FILTER()=='TRUE' 
- Clause for Layers of Oracle Spatial Feature Sources?

I'm trying to produce an overview layer from an Oracle table containing 
a lot of Line Features (> 2 million). The Features, that should be part 
of the overview can be found with a very simple predicate (e.g.: "where 
layername = 'GG'") and are very few (< 1000). My problem is, that 
Mapguide always sends a combined query (simple predicate plus spatial 
query with "extent all"). The Oracle explain plan shows, that internally 
ALL Features are fetched into memory as a result of the spatial query 
only to be filtered with the much "better" simple predicate.
I see this is a problem of the Oracle Cost Based Optimizer.

A nice workaround could be a "Don't use Spatial Filter" Checkbox in 
Mapguide (as available in Oracle Mapviewer).

Would this be possible for the currrent Design?





More information about the Mapguide-users mailing list