The entry cache contains cached entry data. Entry IDs are sent to the entry cache. If the entries that match the entry IDs are in the entry cache, then the results are returned to the client. If the entry cache does not contain the entries that correspond to the entry IDs, the query goes to DB2 in search of the matching entries.
To determine how big your entry cache should be, run your workload with the entry cache set to different sizes and measure the differences in operations per second.
