4 SEM_PERF Package Subprograms

The SEM_PERF package contains subprograms for examining and enhancing the performance of the Resource Description Framework (RDF) and Web Ontology Language (OWL) support in an Oracle database. To use the subprograms in this chapter, you must understand the conceptual and usage information in Chapter 1, "Oracle Semantic Technologies Overview" and Chapter 2, "OWL Concepts".

This chapter provides reference information about the subprograms, listed in alphabetical order.


SEM_PERF.GATHER_STATS

Format

SEM_PERF.GATHER_STATS();

Description

Gathers statistics about RDF and OWL tables and their indexes.

Parameters

None.

Usage Notes

To use this procedure, you must connect as a user with permission to execute it. By default, when Spatial is installed as part of Oracle Database, only the MDSYS user can execute this procedure; however execution permission on this procedure can be granted to users as needed.

This procedure collects statistical information that can help you to improve inferencing performance, as explained in Section 2.2.7. This procedure internally calls the DBMS_STATS.GATHER_TABLE_STATS procedure to collect statistics on RDF- and OWL-related tables and their indexes, and stores the statistics in the Oracle Database data dictionary. For information about using the DBMS_STATS package, see Oracle Database PL/SQL Packages and Types Reference.

Gathering statistics uses significant system resources, so execute this procedure when it cannot adversely affect essential applications and operations.

Examples

The following example gathers statistics about RDF and OWL related tables and their indexes.

EXECUTE SEM_PERF.GATHER_STATS;