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Sharing data across a cache grid: Local and global cache groupsIn addition to being explicitly loaded or dynamic, cache groups are also classified as either local or global.In a local cache group, data in the cache tables is not shared across TimesTen databases even if the databases are members of the same cache grid. Therefore, the databases can have overlapping data because the cache instances are local to a specific grid member. Committed updates on the TimesTen cache tables are propagated to the cached Oracle Database tables without coordination with other grid members. Any cache group type can be defined as a local cache group. A local cache group can be defined either as explicitly loaded or dynamic. Using a local cache group is suitable for reference data that is read frequently and can be present in all grid members and for disjoint data that is logically partitioned for optimal concurrency and throughput. By default, cache groups are local unless they are defined as global.In a global cache group, data in its cache tables are shared across TimesTen databases that are members of the same cache grid. Committed updates to the same data on different grid members are propagated to the Oracle database in the order in which they were issued within the grid to ensure read/write data consistency across the members of the grid.A dynamic AWT cache group and an explicitly loaded AWT cache group can be defined as global cache groups. New cache instances are loaded into the cache tables of a global cache group on demand. Queries on a dynamic AWT global cache group can be satisfied by data from the local grid member on which the query is made, from remote grid members, or from the Oracle database. Queries on an explicitly loaded AWT cache group can be satisfied by data from the local grid member or from remote grid members. Using a global cache group is suitable for updatable data that can only be accessed by or present in one grid member at a time in order to ensure that the data is consistent among both the members of the grid and the Oracle database.See "Global cache groups" for information about creating and using a global cache group.
Sharing data across a cache grid: Local and global cache groups