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Spotlight on DB2 6.10 - User Guide

Spotlight on IBM DB2 LUW (Linux, Unix, and Windows)
New in This Release Getting started with Spotlight on IBM DB2 LUW Desktop features specific to Spotlight on IBM DB2 LUW Spotlight on IBM DB2 LUW drilldowns
About Spotlight on IBM DB2 LUW drilldowns Buffer Pool Analysis drilldown Client Application Analysis drilldown Database Analysis drilldown Database Manager Summary drilldown Diagnostic Log drilldown FCM Analysis drilldown Tablespace Analysis drilldown Top SQL drilldown Operating System drilldown Workload Management Analysis drilldown
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Package Cache graph

About package cache

Package cache is memory that temporarily stores package and section information required for the execution of static and dynamic SQL statements in the database. Caching packages allows the database manager to reduce its internal overhead by eliminating the need to access the system catalog when reloading a package. Likewise, caching dynamic SQL information eliminates the need to compile the statement. In general, caching the section for a static or dynamic SQL statement can improve performance, especially when the same statement is used multiple times by the application.

Sections are held in package cache until one of the following occurs:

  • The database is shut down

  • The package or dynamic SQL statement is invalidated

  • The cache runs out of space

The graph

The Package cache graph contains two series:

  • Hit Rate—Plots the percentage of package cache lookups that were satisfied by data already residing in the package cache. If this hit rate is high, the cache is performing effectively. A smaller ratio might indicate the need to increase package cache.

  • Overflow—Plots, as a percentage of total package cache activity, the number of times the cache overflowed the limits of the memory allocated for it.

The graph title area shows the number of package cache inserts and lookups that occurred during the last monitoring interval.

For related statistical information

The Statistics tab contains entries for all the package cache statistical counts used to generate this graph. The names for these statistics begin with Package Cache. These statistics are derived from the PKG_CACHE data elements that the DB2 snapshot monitor captures.


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