Transient entities are retrieved from Teradata Database and cached on demand. Members are the only class of transient entity. Members are subject to expiration based on their usage frequency and the size of the metadata cache. The maximum metadata cache size can be configured using the MaxMetadataCacheSize registry key. This value sets the maximum number of members that can exist in the cache at any time and defaults to 1,000,000 if not set.
If adding newly-retrieved members to the metadata cache will cause the maximum size to be exceeded, stale entities are ejected. Stale entities are identified based on the frequency of their use, using a Least Frequently Used (LFU) algorithm. Members cached as part of a parent set are ejected together.
If a set of members has been requested and is too large to fit within the cache, the set is retrieved, but is not cached. When the current command has completed execution, the set is discarded. If the maximum metadata cache size is set to 0, all members are applied to this policy, effectively disabling the metadata cache.
Members are retrieved from the cache individually or as part of a parent set. For example, if a group of members are requested as part of the set [Product].[Products].Members, the cached members can fulfill future requests for individual members of the set.