Understanding DMS Event Actions

7 Oracle Metadata Service MDS Performance Tuning 7-1 7 Oracle Metadata Service MDS Performance Tuning This chapter provides tuning tips for Oracle Metadata Service MDS. ■ Section 7.1, About Oracle Metadata Services MDS ■ Section 7.2, Tuning Database Repository ■ Section 7.3, Purging Document Version History ■ Section 7.4, Using Database Polling Interval for Change Detection ■ Section 7.5, Tuning Cache Configuration ■ Section 7.6, Analyzing Performance Impact from Customization ■ Section 7.7, Understanding DMS metrics and Characteristics

7.1 About Oracle Metadata Services MDS

Oracle Metadata Services MDS is an application server and Oracle relational database that keeps metadata in these areas: a file-based repository data, dictionary tables accessed by built-in functions and a metadata registry. One of the primary uses of MDS is to store customizations and persisted personalization for Oracle applications. Oracle Metadata Services MDS is used by components such as Oracle WebCenter Framework and Oracle Application Development Framework ADF to manage metadata. Examples of metadata objects managed by MDS are: JSP pages and page fragments, ADF page definitions and task flows, and customized variants of those objects.

7.2 Tuning Database Repository

For optimal performance of MDS APIs, the database schema for the MDS repository must be monitored and tuned by the database administrator. This section lists some recommended actions to tune the database repository: ■ Collect Schema Statistics ■ Increase Redo Log Size ■ Reclaim Disk Space Note: Most of the Oracle Metadata Service configuration parameters are immutable and cannot be changed at run time unless otherwise specified. 7-2 Oracle Fusion Middleware Performance and Tuning Guide ■ Monitor the Database Performance For additional information on tuning the database, see Optimizing Instance Performance in Oracle Database Performance Tuning Guide.

7.2.1 Collect Schema Statistics

While MDS provides database indexes, they may not be used as expected due to a lack of schema statistics. If performance is an issue with MDS operations such as accessing or updating metadata in database repository, the database administrator must ensure that the statistics are available and current. The following example shows one way that the Oracle database schema statistics can be collected: execute dbms_stats.gather_schema_statsownname = username, estimate_ percent = dbms_stats.auto_sample_size, method_opt= for all columns size auto, cascade=true; For additional information on gathering statistics, see Automatic Performance Statistics in Oracle Database Performance Tuning Guide.

7.2.2 Increase Redo Log Size

The size of the redo log files can influence performance, because the behavior of the database writer and archiver processes depend on the redo log sizes. Generally, larger redo log files provide better performance. Undersized log files increase checkpoint activity and reduce performance. For more information see Sizing Redo Log Files in Oracle Database Performance Tuning Guide.

7.2.3 Reclaim Disk Space

While manual and auto purge operations delete the metadata content from the repository, the database may not immediately reclaim the space held by tables and indexes. This may result in the disk space consumed by MDS schema growing. Database administrators can manually rebuild the indexes and shrink the tables to increase performance and to reclaim disk space. For more information see Reclaiming Unused Space in Oracle Database Performance Tuning Guide.

7.2.4 Monitor the Database Performance

Database administrators must monitor the database for example, by generating automatic workload repository AWR reports for Oracle database to observe lock contention, IO usage and take appropriate action to address the issues. For more information see: ■ Generating Automatic Workload Repository Reports in Oracle Database Performance Tuning Guide ■ Monitoring Performance in Oracle Database Administrators Guide.