14. Using the Query Optimizer : Types of Nodes in a QEP
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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