The Catalog Cache Hit Rate alarm becomes active when the catalog cache hit rate, expressed as a percentage, is low.
The catalog cache is memory that temporarily stores table descriptors--information about tables, views, and aliases in a condensed internal format--found in the database catalog. During SQL statement compilation and dynamic SQL processing, the catalog cache is searched first for descriptors of objects referenced in the SQL statement. If these descriptors are available in cache, the transaction uses descriptor information in cache and avoids having to access the database catalog.
High catalog cache hit rates indicate that the I/O required to compile SQL statements is minimal. When the hit rate is low, catalog cache is not being used efficiently.
The underlying metrics for this alarm can be adjusted to suit your environment by using the Metric Editor.
Consider increasing the size of the catalog cache using the
Access the Databases drilldown. The Caching tab provides statistics about catalog caching on the database.
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