Using Fusion Middleware Control to Enable and Disable Query Caching

7-16 System Administrators Guide for Oracle Business Intelligence Enterprise Edition

7.6.1.2 Caching and Cache Persistence Timing for Specified Physical Tables

You can set a cacheable attribute for each physical table, enabling you to specify whether queries for that table are added to the cache to answer future queries. If you enable caching for a table, then any query involving the table is added to the cache. All tables are cacheable by default, but some tables might not be good candidates to include in the cache unless you use the Cache Persistence Time settings. For example, suppose that you have a table that stores stock ticker data that is updated every minute. You could use the Cache Persistence Time settings to purge the entries for that table every 59 seconds. You can also use the Cache persistence time field to specify how long the entries for this table should be kept in the query cache. This is useful for data sources that are updated frequently. To set the caching attributes for a specific physical table: 1. In the Administration Tool, in the Physical layer, double-click the physical table.

2. In the Physical Table properties dialog, in the General tab, make one of the

following selections: – To enable caching, select Cacheable. – To prevent a table from being cached, deselect Cacheable.

3. To set a cache expiration time, specify a Cache persistence time and specify a unit

of measure days, hours, minutes, or seconds. If you do not want cache entries to automatically expire, select Cache never expires.

4. Click OK.

7.6.1.3 Configure Oracle BI Server Event Polling Tables

Oracle BI Server event polling tables store information about updates in the underlying databases. An application such as one that loads data into a data mart could be configured to add rows to an event polling table each time a database table is updated. The Oracle BI Server polls this table at set intervals and invalidates any cache entries corresponding to the updated tables. Event polling tables can be the sole method of cache management, or they can be used with other cache management schemes. Event tables offer less flexibility about choice of cache entries and the timing of purges. See Section 7.8.1, Setting Up Event Polling Tables on the Physical Databases for more information about event polling tables.

7.6.2 Purging and Maintaining Cache Using ODBC Procedures

The Oracle BI Server provides ODBC-extension functions for purging cache entries. Some of these functions are particularly useful for embedding in an Extract, Transform, and Load ETL task. For example, after a nightly ETL is performed, all Oracle BI Server cache entries can be purged. If only the fact table was modified, then only cache related to that table can be purged. In some cases, you might need to purge the cache entries associated with a specific database. Only administrators have the right to purge cache. Therefore, scripts that call these ODBC-extension functions must run under credentials with administrator privileges. The following ODBC functions affect cache entries that are associated with the repository specified by the ODBC connection: