Maintaining the cache

In this chapter we take a look at the issues that go into maintaining the cache system so as to get optimal performance from it. Three issues arise in maintaining the cache system. The first is related to what exactly should be cached. One should not cache every object requested by the client, doing so may result in wastage of storage. Another issue is the cache size. At some point in time the cache storage will be exhausted, so we will require to replace some older objects so as make place for the newer documents that have to be cached. Finally, we have the consistency problem i.e. how to avoid serving out-of-date documents.

Each issue is described in brief below showing what type of constraints apply to the issue and how they can affect the performance of the cache.