1. Cache Guide
  2. Defining Cache Groups
  3. Read-Only Cache Group
  4. Restrictions with Read-Only Cache Groups

Restrictions with Read-Only Cache Groups

Certain restrictions apply to read-only cache groups.

The following restrictions apply when using a read-only cache group:

  • The cache tables on TimesTen cannot be updated directly.

  • Only the ON DELETE CASCADE and UNIQUE HASH ON cache table attributes can be used in the cache table definitions.

    See ON DELETE CASCADE Cache Table Attribute.

    See Creating a Hash Index on the Primary Key Columns of the Cache Table.

  • A FLUSH CACHE GROUP statement cannot be issued on the cache group.

    See Flushing a User Managed Cache Group.

  • A TRUNCATE TABLE statement issued on a cached Oracle Database table is not automatically refreshed to the TimesTen cache table.

  • A LOAD CACHE GROUP statement can only be issued on the cache group if the cache tables are empty, unless the cache group is dynamic.

    See Manually Loading and Refreshing a Cache Group.

    See Creating a Dynamic Cache Group with the DYNAMIC Keyword.

  • The autorefresh state must be PAUSED before you can issue a LOAD CACHE GROUP statement on the cache group, unless the cache group is dynamic, in which case the autorefresh state must be PAUSED or ON. The LOAD CACHE GROUP statement cannot contain a WHERE clause, unless the cache group is dynamic, in which case the WHERE clause must be followed by a COMMIT EVERY n ROWS clause.

    See Automatically Refreshing a Cache Group.

    See Using a WHERE Clause.

  • The autorefresh state must be PAUSED before you can issue a REFRESH CACHE GROUP statement on the cache group. The REFRESH CACHE GROUP statement cannot contain a WHERE clause.

    See Manually Loading and Refreshing a Cache Group.

  • All tables and columns referenced in WHERE clauses when creating, loading or unloading the cache group must be fully qualified. For example:

    owner.table_name and owner.table_name.column_name

  • Least recently used (LRU) aging cannot be specified on the cache group, unless the cache group is dynamic where LRU aging is defined by default.

    See LRU Aging in TimesTen Classic.

  • Read-only cache groups cannot cache Oracle Database views or materialized views.