You can display the hit rate of the caches in the Database Manager GUI. These hit rates show you whether the caches have been configured with enough space. The hit rates for the data cache and the converter are particularly important.
The database instance is in the ONLINE operational state.
Select the required database instance in the list of database instances. Choose Instance ® Information ® Caches.
Type |
Cache type |
Accesses |
Total number of accesses |
Successful |
Number of successful accesses |
Unsuccessful |
Number of unsuccessful accesses |
Hit Rate (%) |
Hit rate (number of hits as a percentage of the total number of accesses) |
The hit rate of the data cache should be at least 99% and the converter hit rate should be at least 98%.
Lower hit rates can occur for a short time, for example when tables are read for the first time, or when the table does not fit into 10% of the data cache in the case of repeated table scans.
If the values are permanently lower than the recommended percentage, this is a sign of poor performance and the general database parameter CACHE_SIZE must be adjusted accordingly.