Disk Space Costs of Caching

7-12 System Administrators Guide for Oracle Business Intelligence Enterprise Edition The logical event queue in the global cache on the shared storage is composed of seeding and purging events from individual Oracle BI Server nodes. The queue is sorted according to the timestamp of the events. Hence, clocks on all Oracle BI Server nodes participating in cluster must be synchronized. Each Oracle BI Server node polls the global cache on a periodic basis for new cache entries. This polling frequency is configurable. A snapshot of the queued logical events on the shared storage are pulled back to the node and a local logical event queue is constructed and then processed. Because the query cache result set tends to get large, network bandwidth might pose a constraint. Therefore, the following must be chosen carefully: ■ The set of caches that qualify for seeded cache ■ The time interval for BI nodes to pick up seeded caches from shared storage to avoid network congestion The primary global cache parameters are configured in Fusion Middleware Control. Additional, optional parameters are configured in the NQSConfig.INI file for each Oracle BI Server node that participates in the cluster. For more information about configuring these parameters, see Section 7.5.4, Using Fusion Middleware Control to Set Global Cache Parameters and Section 7.5.5, Manually Editing Additional Global Cache Parameters. A seeding or purging procedure is submitted to a specific Oracle BI Server node. If that Oracle BI Server is a node in a BI cluster and the global cache parameters have been defined in Oracle BI Server configuration files, then the seeding or purging events are propagated across all Oracle BI Server nodes that participate in the same clustered environment.

7.5 Configuring Query Caching

You configure cache storage and other parameters in Fusion Middleware Control and in the NQSConfig.INI file, for both the query cache and the global cache. You also must decide on a strategy for flushing outdated cache entries; see Section 7.6, Monitoring and Managing the Cache for more information. This section contains the following topics: ■ Section 7.5.1, Using Fusion Middleware Control to Enable and Disable Query Caching ■ Section 7.5.2, Using Fusion Middleware Control to Set Query Cache Parameters ■ Section 7.5.3, Manually Editing Additional Query Cache Parameters ■ Section 7.5.4, Using Fusion Middleware Control to Set Global Cache Parameters ■ Section 7.5.5, Manually Editing Additional Global Cache Parameters Note: The process of populating or purging seeded caches across all Oracle BI Server nodes that participate in the cluster does not occur in real time, and the elapse of the process is affected by multiple factors, such as the predefined polling interval, network bandwidth, and CPU loads.