A row source is a set of rows returned by a step in the execution plan. A SQL operator acts on a row source.

A unary operator acts on one input, as with access paths. A binary operator acts on two outputs, as with joins.

This part contains the following chapters:

• Optimizer Access Paths
  An access path is a technique used by a query to retrieve rows from a row source.
• Joins
  Oracle Database provides several optimizations for joining row sets.