EAServer supports object and query caching for EJB entity beans and entity components that use automatic persistence. Caching can improve performance by minimizing the number of database select queries required for ejbLoad operations, finder method invocations, and ejbSelect method invocations. Most database applications are governed by the 80:20 rule: 80% of users access 20% of the data. Object caching increases performance and scalability by allowing faster access to the most recently used data.
Assuming that the database access is the principal bottleneck, the expected performance gain falls in these ranges, depending on the ratio of update to read-only transactions:
1.5 to 2 times faster for applications where most transactions are updates.
3 to 30 times faster for applications where most transactions are read-only.
Besides the transaction mix, the actual performance gain depends on:
The size of the database table
The size of the object and query caches
The cache time out value
In summary, the best use case for caching is data that is static. If the data changes often, the overhead of updating caches can outweigh the performance benefits of caching. If the data is updated too frequently, soft locking or hard locking may yield better performance. Furthermore, the data consistency requirements dictate how cached data can be used. Decide how much consistency you require, then optimize within those constraints.
Cache synchronization can be enabled to minimize the occurrences of transaction rollback due to overlapping updates. EAServer supports cache synchronization between servers in a cluster and from the database to EAServer. In some cases, the overhead of synchronization may outweigh the benefits incurred.
