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Usage Notes
Examples
SDO_SAM.TILED_AGGREGATES
zero_agg_tiles
Specify 0 to exclude tiles that have a value of 0 for the computed aggregate, or specify
1 to return all tiles. The default value is 0, which ensures that only tiles with a nonzero
aggregate value are returned.
xdivs
The number of times that the extent in the first dimension is divided, such that the
total number of parts is xdivs + 1. For example, if you specify 10 for xdivs, the
extent of the first dimension is divided into 11 parts.
ydivs
The number of times that the extent in the second dimension is divided, such that the
total number of parts is ydivs + 1. For example, if you specify 10 for ydivs, the
extent of the second dimension is divided into 11 parts.
This function is similar to SDO_SAM.AGGREGATES_FOR_LAYER, but the results are
dynamically generated using tiling information. Given a theme_name table, the tiling
domain is determined. Based on the tiling_level value or the xdivs and ydivs
values, the necessary tiles are generated. For each tile geometry, thematic aggregates
are computed as described in the Usage Notes for SDO_SAM.AGGREGATES_FOR_
LAYER.
You must specify either the tiling_level parameter or both the xdivs and ydivs
parameters. If you specify all three of these parameters, the tiling_level parameter
is ignored and the xdivs and ydivs parameters are used.
If you specify the xdivs and ydivs parameters, the total number of grids (tiles)
returned is (xdivs+1)*(ydivs+1).
This function returns an object of type SDO_REGAGGRSET. The SDO_REGAGGRSET
object type is defined as:
TABLE OF SDO_REGAGGR
The SDO_REGAGGR object type is defined as:
Name Null? Type
----------------------------------------- -------- ----------------------------
REGION_ID VARCHAR2(24)
GEOMETRY MDSYS.SDO_GEOMETRY
AGGREGATE_VALUE NUMBER
The following example computes the sum of the population rows of POLY_4PT_TEMP
table intersecting with each tile. The extent of the POLY_4PT_TEMP table stored in the
USER_SDO_GEOM_METADATA view is used as the domain, and a tiling level of 2 is
used (that is, the domain is divided into 16 tiles).
SELECT a.geometry, a.aggregate_value
from TABLE(sdo_sam.tiled_aggregates('POLY_4PT_TEMP',
'GEOMETRY', 'SUM', 'POPULATION', 2)) a;
GEOMETRY(SDO_GTYPE, SDO_SRID, SDO_POINT(X, Y, Z), SDO_ELEM_INFO, SDO_ORDINATES)
--------------------------------------------------------------------------------
AGGREGATE_VALUE
---------------
SDO_GEOMETRY(2003, 8307, NULL, SDO_ELEM_INFO_ARRAY(1, 1003, 3), SDO_ORDINATE_ARR
AY(-180, -90, -90, -45))
SDO_SAM Package (Spatial Analysis and Mining) 29-19