2.4 GeoRaster System Data Views (xxx_SDO_GEOR_SYSDATA)

GeoRaster uses a system data table (also called the sysdata table) to maintain the relationship between GeoRaster tables and their related raster data tables.

Each GeoRaster object (if it is not null) has a related raster data table, and it might have other information, such as ground control points (GCPs) and value attribute tables (VATs).

For a given user, the raster data table name plus the rasterID uniquely identify a GeoRaster object. It is possible for many GeoRaster objects (each with a different rasterID value) in one GeoRaster table to share one raster data table.

Whenever a new GeoRaster object (including empty and blank GeoRaster objects) is created, a raster data table is assigned to it and a rasterID value is assigned. All SDO_GEORASTER objects (except atomic null objects) are automatically recorded in the system data table when they are created.

The GeoRaster sysdata table is under the MDSYS schema. Most of the information in the GeoRaster system data table is available for retrieval through system data views, and thus it can be used as a dictionary or a catalog of all GeoRaster objects in a GeoRaster database. Each GeoRaster user has the following system data views available in the schema associated with that user:

• USER_SDO_GEOR_SYSDATA contains system data for all GeoRaster objects owned by the current user.

• ALL_SDO_GEOR_SYSDATA contains system data for all GeoRaster objects accessible by the current user.

The GeoRaster sysdata table and the USER_SDO_GEOR_SYSDATA and ALL_SDO_GEOR_SYSDATA views should never be modified directly by users, although they are updated by the DML trigger that is automatically created on each SDO_GEORASTER column in each GeoRaster table.

The USER_SDO_GEOR_SYSDATA view has the following definition:

(
   TABLE_NAME            VARCHAR2(128),
   COLUMN_NAME           VARCHAR2(1024),
   METADATA_COLUMN_NAME  VARCHAR2(1024),
   RDT_TABLE_NAME        VARCHAR2(128),
   RASTER_ID             NUMBER,
   OTHER_TABLE_NAMES     SDO_STRING_ARRAY
);

The ALL_SDO_GEOR_SYSDATA view has all columns in the USER_SDO_GEOR_SYSDATA view, but it also has an OWNER column identifying the schema that owns the table specified in the TABLE_NAME column.

This section describes each of the columns common to both views. Note that for VARCHAR2 data in any columns, names are stored in all uppercase characters.

• TABLE_NAME Column
  
• COLUMN_NAME Column
  
• METADATA_COLUMN_NAME Column
  
• RDT_TABLE_NAME Column
  
• RASTER_ID Column
  
• OTHER_TABLE_NAMES Column
  

2.4.1 TABLE_NAME Column

The TABLE_NAME column contains the name of a GeoRaster table that has at least one column of type SDO_GEORASTER.

2.4.2 COLUMN_NAME Column

The COLUMN_NAME column contains the name of a column of type SDO_GEORASTER in the GeoRaster table specified in the TABLE_NAME column.

2.4.3 METADATA_COLUMN_NAME Column

The METADATA_COLUMN_NAME column is ignored for the current release.

2.4.4 RDT_TABLE_NAME Column

The RDT_TABLE_NAME column contains the name of the raster data table associated with the table and column specified in the TABLE_NAME and COLUMN_NAME columns.)

2.4.5 RASTER_ID Column

The RASTER_ID column contains a number that, together with the RDT_TABLE_NAME column value, uniquely identifies each GeoRaster object.

2.4.6 OTHER_TABLE_NAMES Column

The OTHER_TABLE_NAMES column is ignored for the current release.