This Part explains how to optimize queries using In-Memory Expressions, join groups, and In-Memory aggregation. It also explains how the IM column store repopulates modified data.

This Part contains the following chapters:

• Optimizing Queries with In-Memory Expressions
  In the context of the IM column store, an expression is a combination of one or more values, operators, and SQL or PL/SQL functions (DETERMINISTIC only) that resolve to a value.
• Optimizing Joins with Join Groups
  A join group is a user-created dictionary object that lists two columns that can be meaningfully joined.
• Optimizing Joins with In-Memory Aggregation
  Starting with Oracle Database 12c Release 1 (12.1.0.2), In-Memory Aggregation (IM aggregation) enables queries to aggregate while scanning.
• Optimizing Repopulation of the IM Column Store
  The IM column store periodically refreshes objects that have been modified. You can control this behavior using initialization parameters and the DBMS_INMEMORY package.