Cache Group Types

There are several cache group types from which you can choose depending on the application needs.

TimesTen supports the following types of cache groups:

• Read-only cache group

  A read-only cache group enforces a caching behavior in which committed changes on cached tables in the Oracle database are automatically refreshed to the cache tables in the TimesTen database. Using a read-only cache group is suitable for reference data that is heavily accessed by applications.

  The two types of read-only cache groups are:

  • Static read-only cache group: With a static read-only cache group, you use manual load requests to load data. You can use manual refresh requests. However, most read-only cache groups use autorefresh operations to refresh modified data at specified time intervals. When using autorefresh, the manual refresh requests are not necessary.

  • Dynamic read-only cache group: With a dynamic read-only cache group, the application relies on data dynamically loading when data is requested with a qualified SELECT... WHERE SQL statement. Most read-only cache groups use autorefresh operations to refresh modified data at specified time intervals.

  Log-based cache groups offer an alternative to traditional read-only caching by using redo logs to synchronize data between Oracle and TimesTen. This approach is well-suited for both static and dynamic cache groups, where the data is regularly refreshed and kept in sync with Oracle. See Log-Based Read-Only Cache Groups with TimesTen Replication.

  See Read-Only Cache Group.

• Asynchronous WriteThrough (AWT) cache group

  An AWT cache group enforces a caching behavior in which committed changes on cache tables in the TimesTen database are automatically propagated to the cached tables in the Oracle database in asynchronous fashion. Using an AWT cache group is suitable for high speed data capture and online transaction processing.

  See Asynchronous WriteThrough (AWT) Cache Group.

Other types of cache groups include:

• Synchronous writethrough (SWT) cache group

  An SWT cache group enforces a caching behavior in which committed changes on cache tables in the TimesTen database are automatically propagated to the cached tables in the Oracle database in synchronous fashion.

  See Synchronous WriteThrough (SWT) Cache Group.

• User managed cache group

  A user managed cache group defines customized caching behavior.

  For example, you can define a cache group that does not use automatic refresh or automatic propagation where committed changes on the cache tables are manually propagated or flushed to the cached Oracle Database tables.

  You can also define a cache group that uses both automatic propagation in synchronous fashion on every table and automatic refresh.

  TimesTen supports user managed cache groups.

  See User Managed Cache Group.

• Hybrid cache group

  All other cache groups require multiple table cache groups to have strict parent-child relationships for all tables on a TimesTen database as well as the Oracle database. With hybrid cache groups, the cache tables on a Oracle database must be related, but the root (parent) table must only exist on the TimesTen database. That is, 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.

  See Hybrid Cache Group.