Sparse and complete cache

WebSphere® eXtreme Scale can be used as a sparse cache or a complete cache. A sparse cache only keeps a subset of the total data, while a complete cache keeps all of the data. and can be populated lazily, as the data is needed. Sparse caches are normally accessed using keys (instead of indexes or queries) because the data is only partially available.

Sparse cache

When a key is not present in a sparse cache, or the data is not available and a cache miss occurs, the next tier is invoked. The data is fetched, from a database for example, and is inserted into the data grid cache tier. If you are using a query or index, only the currently loaded values are accessed and the requests are not forwarded to the other tiers.

Complete cache

A complete cache contains all of the required data and can be accessed using non-key attributes with indexes or queries. A complete cache is preloaded with data from the database before the application tries to access the data. A complete cache can function as a database replacement after data is loaded. Because all of the data is available, queries and indexes can be used to find and aggregate data.