Types of Nodes in a QEP
Each node in a QEP has detailed information associated with it, depending on the type of node.
The types of nodes are as follows:
• Orig (or leaf) node--describes a particular table
• Proj-rest node--describes the result of a projection and/or WHERE clause restriction applied to a subsidiary node
• Join node--describes a join. One of the following strategies is used:
– Cartesian product
– Full sort merge
– Partial sort merge
– Key and tid lookup joins
– Subquery joins
• Exchange node--describes a point at which separate plan fragments execute concurrently on different threads as part of a parallel query plan