QueryTask Performance issues with SHAPE field

[JohanFerguson]

Hi There

I have built a rest service within ArcGIS Server 9.3.1 which i want to query using the QueryTask in the ArcGIS API for Silverlight 3. When i specify my output fields and those fields doesnt include the "Shape" field , the query performs pretty quick with no issues.

As soon as i include the "Shape" field within my output fields I experience slow performane.
Does anybody know how this might occure ? am i missing something ? or do i do something wrong ?

[DominiqueBroux]

By including the SHAPE field, it means that the geometry is serialized, transferred and deserialized. So, depending on the number of objects returned by your query,  you can slow down the performance (also depending on type of geometry, a point is lighter than a polyline or a polygon).

This is the reason why in the query sample (http://help.arcgis.com/en/webapi/silverlight/samples/start.htm#AttributeQuery), a first query is done to get the state names without the geometry and then, when the user selects one state, a new query is done on this state.

I tested the first query with all fields instead of just the state name. In this case the request returns about 220kb instead of 616b ==> ratio = 360.