The cache index

In either a memory or disk cache, Caching Proxy also uses system memory space to hold an index of the cache, which reduces the processing time to find cached files.

Caching Proxy's cache directory structure and its lookup methods are different from those of other proxy servers. Caching Proxy maintains an index in memory with information about the files in the cache. Using RAM for lookup instead of a disk or other medium results in faster file lookup and retrieval.

The index includes URLs, cache locations, and expiry information for cached objects. For this reason, the amount of memory necessary to hold the index is proportional to the number of objects in the cache.

When a request is received from a client, the proxy checks the cache index in memory for that URL.