4.5 Querying and Updating GeoRaster Metadata

You can query metadata for a GeoRaster object, and you can update many attributes of the metadata.

You can use many functions, most of whose names start with get, to query the metadata and ancillary information (for example, SDO_GEOR.getTotalLayerNumber and SDO_GEOR.hasPseudoColor).

You can use several subprograms, most of whose names start with set, to update metadata and ancillary data (for example, SDO_GEOR.setSRS and SDO_GEOR.setColorMap).

For many of the get functions, there is a corresponding procedure, whose name starts with set, to set, modify, or delete the value of a metadata attribute. For most set procedures, to delete the value of the metadata attribute that the procedure is designed to modify, specify a null value for the attribute. For example, to delete the bin table for a layer of a GeoRaster object, call the SDO_GEOR.setBinTable procedure and specify a null tableName parameter. However, in most cases you cannot specify a null value for other related attributes. For example, you cannot specify a null layerNumber parameter in a call to the SDO_GEOR.setBinTable procedure.

Note the following recommendations, requirements, and restrictions:

• Most GeoRaster metadata can also be retrieved using XMLType methods or XML-specific SQL functions, such as extract, and be modified using XQuery Update. However, if a GeoRaster get or set subprogram exists for the metadata attribute you want to retrieve or change, use the GeoRaster subprogram instead of an XMLType interface, because the GeoRaster subprograms validate any changes before they are made. If you do call XMLType methods or XML-specific SQL functions to update metadata, you should validate the GeoRaster object before you commit the transaction.

• Never directly set the metadata to be null.

• Do not directly update the rasterType attribute of a GeoRaster object; instead, call the SDO_GEOR.setRasterType procedure.

• To change the raster data table name, use the SDO_GEOR_UTL.renameRDT procedure.

• In general, you should not directly update the attributes of a GeoRaster object, except for the spatialExtent attribute.

• After updating a GeoRaster object's metadata or cell data (or both) and before you commit a database transaction, you should call the SQL UPDATE statement to update the GeoRaster object (see Updating GeoRaster Objects Before Committing).