9.34.6.Defining a Geometry Index
The below sequence defines a table called geo and a geometry index on its geo column.
create table GEO (ID bigint, GEO any, primary key (ID)) alter index geo on geo partition (id int); CREATE TABLE GEO_INX ( X real no compress, Y real no compress, X2 real no compress, Y2 real no compress, id bigint no compress, primary key (X, Y, X2, Y2, id)) ALTER INDEX geo_inx ON geo_inx PARTITION (id int); INSERT INTO sys_vt_index ( vi_table, vi_index, vi_col, vi_id_col, vi_index_table, vi_id_is_pk, vi_options) VALUES ('DB.DBA.GEO', 'GEO', 'GEO', 'ID', 'DB.DBA.GEO_INX', 1, 'G'); -- Reload the changed schema __ddl_changed ('DB.DBA.GEO');
A geometry index is a table of always five columns, the first 4 are the lower x, y and higher x, y of the object's bounding box, id is the identifier of the object, a foreign key into the table holding the geometries. In a cluster setting the geometry index must be partitioned on the id column. The columns of a geometry index must never be compressed, hence the mandatory no compress declaration.
Geometry indices are declared in the sys_vt_index table, which also declares text indices. The G in the options column declares that this is a geometry index.
A geometry index will be used when appropriate. The table holding the R tree with the bounding boxes should not normally be accessed directly. Explicit selects from a geometry index table with conditions on the columns will not generally work since the collation is not linear as in a regular index. Inserts by means other than geo_insert are not allowed.