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

Class PruneApplyColumns

java.lang.Object

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

io.prestosql.sql.planner.iterative.rule.PruneApplyColumns

All Implemented Interfaces:

Rule<ProjectNode>

public class PruneApplyColumns
extends ProjectOffPushDownRule<ApplyNode>

This rule restricts the outputs of ApplyNode's input and subquery based on which ApplyNode's output symbols are referenced.

A symbol from input source can be pruned, when - it is not a referenced output symbol - it is not a correlation symbol - it is not referenced in subqueryAssignments

A symbol from subquery source can be pruned, when it is not referenced in subqueryAssignments.

A subquery assignment can be removed, when its key is not a referenced output symbol.

Note: this rule does not remove any symbols from the correlation list. This is responsibility of PruneApplyCorrelation rule.

Transforms:

 - Project (i1, r1)
      - Apply
          correlation: [corr]
          assignments:
              r1 -> a in s1,
              r2 -> b in s2,
          - Input (a, b, corr)
          - Subquery (s1, s2)
 

Into:

 - Project (i1, r1)
      - Apply
          correlation: [corr]
          assignments:
              r1 -> a in s1,
          - Project (a, corr)
              - Input (a, b, corr)
          - Project (s1)
              - Subquery (s1, s2)
 

Nested Class Summary

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

Rule.Context, Rule.Result

Constructor Summary

Constructors

Constructor	Description
PruneApplyColumns()

Method Summary

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

PruneApplyColumns

public PruneApplyColumns()

Method Detail

pushDownProjectOff

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

Specified by:

pushDownProjectOff in class ProjectOffPushDownRule<ApplyNode>