SDO_AGGR_UNION gives ODCI errors

Question

I have a Oracle spatial table having over 2 millon records. I need to aggregate all the buffer geometries based on names such that for each name there will be only one aggregated geometry. There are around 5000 distinct name.
I am running the following query,
SELECT NAME, COUNT(GEOM),
     SDO_AGGR_UNION(MDSYS.SDOAGGRTYPE
     (SDO_GEOM.SDO_BUFFER
     (GEOM, 100.0, 0.5, 'UNIT=FOOT'), 0.05))
FROM GEOM_TABLE
GROUP BY NAME;
I am getting the following errors,
ORA-29913: error in executing ODCIAGGREGATEMERGE callout
ORA-29913: error in executing ODCIAGGREGATEITERATE callout
ORA-13347: the coordinates defining an arc are not distinct
When I am limiting the number of geometries during aggregation it is working fine but failing with real data. Since SDO_AGGR_UNION is very slow in performance, what are the other available solutions. SDO_AGGR_SET_UNION doesn't either.
Regards,
Ananda

Answer 1

You may split your query into two, to measure their performance:
CREATE TABLE BUFF_GEOM_TABLE (NAME VARCHAR2(***), GEOM SDO_GEOMETRY);
INSERT INTO BUF_GEOM_TABLE SELECT NAME,  SDO_GEOM.SDO_BUFFER(GEOM, 100.0, 0.5, 'UNIT=FOOT'), 0.05)
FROM GEOM_TABLE;
SELECT NAME, COUNT(GEOM),
     SDO_AGGR_UNION(MDSYS.SDOAGGRTYPE
     (GEOM, 0.05))
FROM BUFF_GEOM_TABLE
GROUP BY NAME;
If the bottleneck is with SDO_AGGR_UNION, you may have some options:
If you have 12c Oracle Spatial, you can enable the Vector Performance Accelerator (VPA) feature by setting the
SPATIAL_VECTOR_ACCELERATION database system parameter to the value TRUE.
ALTER SYSTEM/SESSION SET SPATIAL_VECTOR_ACCELERATION = TRUE;
If you have 11gR2, you may use SDO_AGGR_SET_UNION. Please see an example of SDO_AGGR_SET_UNION:
Spatial Aggregate Functions