1. Cache Guide
  2. Defining Cache Groups
  3. Hybrid Cache Group

Hybrid Cache Group

A hybrid cache group is a dynamic read-only cache group where the root table is created in the TimesTen database and does not exist in the Oracle database.

A cache group is a set of tables related through foreign keys that cache data from tables in an Oracle database. Each cache group includes one root table that does not reference any of the other tables. Foreign keys on all other cache tables in the cache group reference exactly one other table in the cache group. In other words, the foreign key relationships form a tree. For multiple table cache groups, you determined the relationship between the tables by defining which table is the root table, which tables are direct child tables of the root table, and which tables are the child tables of other child tables. Historically, all tables within the cache group exist in the Oracle database.

With a hybrid cache group, you can dynamically load from cache tables that do not have a root table on the Oracle database. A hybrid cache group is a dynamic read-only cache group where the root table is created in the TimesTen database and does not exist in the Oracle database.

  • TimesTen creates the root table on the TimesTen database from the definition of the hybrid cache group. Note that you should not create this table on the Oracle database.

  • The only columns allowed in the root table definition are the columns defining the primary key.

  • All other cache tables must exist in the Oracle database.

  • The root table must be referenced by at least one child table through a foreign key relationship.

The following sections describe how to use a hybrid cache group: