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

Class PruneUnnestColumns

java.lang.Object

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

io.prestosql.sql.planner.iterative.rule.PruneUnnestColumns

All Implemented Interfaces:

Rule<ProjectNode>

public class PruneUnnestColumns
extends ProjectOffPushDownRule<UnnestNode>

Absorb pruning projection into the node. Remove any unnecessary replicate symbols and ordinality symbol. Symbol is considered unnecessary if it is: - not referenced by the parent node - not used in filter expression Note: mappings are not eligible for pruning.

Transforms:

  - Project (c)
      - Unnest:
          replicate (a, b, c, d)
          mappings (d -> d1)
          ordinality (ord)
          filter (a > 5)
          - Source (a, b, c d)
 

into:

  - Project (c)
      - Unnest:
          replicate (a, c)
          mappings (d -> d1)
          ordinality ()
          filter (a > 5)
          - Source (a, b, c, d)
  

Note: If, as a result of this rule, any of source's symbols became unreferenced, it will be addressed by PruneUnnestSourceColumns 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
PruneUnnestColumns()

Method Summary

Modifier and Type	Method	Description
protected Optional<PlanNode>	pushDownProjectOff(Rule.Context context, UnnestNode unnestNode, 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

PruneUnnestColumns

public PruneUnnestColumns()

Method Detail

pushDownProjectOff

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

Specified by:

pushDownProjectOff in class ProjectOffPushDownRule<UnnestNode>