Catalog Cache Hitrate

Catalog cache hitrate <percentage>%, <number> of <number> accesses failed


The hit rate when accessing the catalog cache in which the parsed SQL statements are administered is too low. In a running database application, the catalog cache hit rate should be about 90%. If new program components or programs are started, the hit rate can drop temporarily to a very low level. However, the average over a 15-minute period should not drop below 85%.

User Response

The size of the catalog cache should be about 100 pages for each database session. You can check this using the general database parameter MAXUSERTASKS and the special database parameter CAT_CACHE_SUPPLY.

The catalog cache is enlarged dynamically by the active database sessions, and released again with a RELEASE statement. You can determine the current cache sizes using the SQL statement SELECT * FROM CONNECTEDUSERS.

If sessions need significantly more than 100 pages, we recommend that in the medium term you increase the catalog cache accordingly, memory permitted.