Oracle¶

Using loose bounding box¶

When the loose bbox option is set, only the bounding box of a geometry is used. This results in a significant performance gain. The downside is that some geometries may be considered inside of a bounding box when they are technically not.

If the primary use of the database is through Web Map Service this flag can be set safely since a loss of some accuracy is usually acceptable. However if using Web Feature Service and making use of BBOX filtering capabilities, this flag should not be set.

Using the geometry metadata table¶

The Oracle data store will, by default, look into the MDSYS.USER_SDO* and MDSYS.ALL_SDO* views to determine the geometry type and native SRID of each geometry column. Those views are automatically populated with information about the geometry columns stored in tables that the current user owns (for the MDSYS.USER_SDO* views) or can otherwise access (for the MDSYS.ALL_SDO* views).

There are a few hiccups in this process:

• if the connection pool user cannot access the tables (because impersonation is used) the MDSYS views will be empty, making it impossible to determine either the geometry type and the native SRID
• the geometry type can be specified only while building the spatial indexes, as a index constraint, however such information is often not included when creating the indexes
• the views are populated dynamically based on the current user, if the database has thousands of tables and users the views can become very slow

Starting with GeoServer 2.1.4 the administrator can address the above issues by manually creating a geometry metadata table describing each geometry column, and then indicate its presence among the Oracle data store connection parameter named Geometry metadata table (either as a simple table name, or a schema qualified one). The table has the following structure (the table name is free, just indicate the one chosen in the data store connection parameter):

CREATE TABLE GEOMETRY_COLUMNS(
   F_TABLE_SCHEMA VARCHAR(30) NOT NULL,
   F_TABLE_NAME VARCHAR(30) NOT NULL,
   F_GEOMETRY_COLUMN VARCHAR(30) NOT NULL,
   COORD_DIMENSION INTEGER,
   SRID INTEGER NOT NULL,
   TYPE VARCHAR(30) NOT NULL,
   UNIQUE(F_TABLE_SCHEMA, F_TABLE_NAME, F_GEOMETRY_COLUMN),
   CHECK(TYPE IN ('POINT','LINE', 'POLYGON', 'COLLECTION', 'MULTIPOINT', 'MULTILINE', 'MULTIPOLYGON', 'GEOMETRY') ));

When the table is present the store wil first search it for information about each geometry column to be classified, and fall back on the MDSYS views only if such table does not contain any information.