Logical Properties of Query Plans¶

Presto implements a framework for associating logical properties with the result sets produced by the nodes of a query plan. These logical properties might either derive from constraints defined on tables, or from operations performed by intermediate nodes in the query plan such as aggregations, limits, or the application of predicates. The Presto optimizer may then use these logical properties to perform optimizations such as removing redundant operations or other logical transformations.

The propagation of logical properties in query plans is enabled by the exploit_constraints session property or optimizer.exploit_constraints configuration property set in etc/config.properties of the coordinator. Logical property propagation is enabled by default.

Types of Logical Properties¶

Presto detects and propagates the following logical properties:

• KeyProperty - A collection of distinct attributes that hold for a final or intermediate result set produced by a plan node.

• MaxCardProperty - A provable maximum number of rows in a final or intermediate result set produced by a plan node.

• EquivalenceClassProperty - Classes of equivalent variable and constant references that hold for a final or intermediate result set produced by a plan node.