Query multiple SDO_PC objects

Question

Hi,
I have a collection of SDO_PC objects in my BASE table (with each SDO_PC object having the appropriate BLKTAB# associated with it).
I know I can use a query such as:
select sdo_pc_pkg.to_geometry(
a.points, -- point LOB
a.num_points, -- # of points in the LOB
3, -- total dimensionality
4269 -- SRID
) from blktab10 a where blk_id<3;
to select a geometry from 1 PC object but I would like to be able to query all point clouds I have and return a geometry (or a collection of geometries) based on my query. Ex: Select sdo_pc_pkg.to_geometry (...) from base where id < 10.
I would then expand this idea and have views of the BASE table to partition data and then I would like to query each view as if it were 1 blktable to do something like: Return geometry for all points in (PARTIAL_VIEW_OF_BASE) that are within 5 miles of some geometry.
Is there an easy way (or any way) to do this?
Thanks a lot,
Dan

Answer 1

The sdo_pc_pkg.to_geometry function is not built for querying against a bunch of point clouds.
If you want to combine the results from different blocks into one geometry object, you can do that by using an
aggregate function on the geometries returned by each call to to_geometry() function. But this can get
very expensive.
You can use the spatial index on the blk table to find all the blocks which are within 5 miles of some geometry
and then only select those blocks to call the to_geoemtry function.
siva