Package io.prestosql.sql.planner.iterative.rule

Class PruneUnionColumns

java.lang.Object

io.prestosql.sql.planner.iterative.rule.ProjectOffPushDownRule<UnionNode>

io.prestosql.sql.planner.iterative.rule.PruneUnionColumns

All Implemented Interfaces:

Rule<ProjectNode>

public class PruneUnionColumns
extends ProjectOffPushDownRule<UnionNode>

Transforms

 - Project (a)
      - Union
        output mappings: {a->c, a->e, b->d, b->f}
          - Source (c, d)
          - Source (e, f)
 

into:

 - Project (a)
      - Union
        output mappings: {a->c, a->e}
          - Source (c, d)
          - Source (e, f)
 

Note: as a result of this rule, the UnionNode's sources are eligible for pruning outputs. This is accomplished by PruneUnionSourceColumns rule.

Nested Class Summary

Nested classes/interfaces inherited from interface io.prestosql.sql.planner.iterative.Rule

Rule.Context, Rule.Result

Constructor Summary

Constructors

Constructor	Description
PruneUnionColumns()

Method Summary

Modifier and Type	Method	Description
protected Optional<PlanNode>	pushDownProjectOff(Rule.Context context, UnionNode unionNode, Set<Symbol> referencedOutputs)

Methods inherited from class io.prestosql.sql.planner.iterative.rule.ProjectOffPushDownRule

apply, getPattern

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface io.prestosql.sql.planner.iterative.Rule

isEnabled

Constructor Detail

PruneUnionColumns

public PruneUnionColumns()

Method Detail

pushDownProjectOff

protected Optional<PlanNode> pushDownProjectOff(Rule.Context context,
                                                UnionNode unionNode,
                                                Set<Symbol> referencedOutputs)

Specified by:

pushDownProjectOff in class ProjectOffPushDownRule<UnionNode>