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

Class PruneGroupIdColumns

java.lang.Object

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

io.prestosql.sql.planner.iterative.rule.PruneGroupIdColumns

All Implemented Interfaces:

Rule<ProjectNode>

public class PruneGroupIdColumns
extends ProjectOffPushDownRule<GroupIdNode>

This rule prunes GroupIdNode's aggregationArguments.

Transforms:

 - Project (a, key_1, key_2, group_id)
      - GroupId
          grouping sets: ((key_1), (key_2))
          aggregation arguments: (a, b)
          group id symbol: group_id
           - Source (a, b, key_1, key_2)
 

Into:

 - Project (a, key_1, key_2, group_id)
      - GroupId
          grouping sets: ((key_1), (key_2))
          aggregation arguments: (a)
          group id symbol: group_id
           - Source (a, b, key_1, key_2)
 

Note: this rule does not prune any grouping symbols. Currently, GroupIdNode is only used in regard to AggregationNode. The presence of an AggregationNode in the plan ensures that the grouping symbols are referenced. This rule could be extended to prune grouping symbols.

Note: after pruning an aggregation argument, the child node of the GroupIdNode becomes eligible for symbol pruning. That is performed by the rule PruneGroupIdSourceColumns.

Nested Class Summary

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

Rule.Context, Rule.Result

Constructor Summary

Constructors

Constructor	Description
PruneGroupIdColumns()

Method Summary

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

PruneGroupIdColumns

public PruneGroupIdColumns()

Method Detail

pushDownProjectOff

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

Specified by:

pushDownProjectOff in class ProjectOffPushDownRule<GroupIdNode>