org.apache.calcite.plan

Class SubstitutionVisitor.TrivialRule

java.lang.Object

org.apache.calcite.plan.SubstitutionVisitor.UnifyRule

org.apache.calcite.plan.SubstitutionVisitor.AbstractUnifyRule

org.apache.calcite.plan.SubstitutionVisitor.TrivialRule

Enclosing class:

SubstitutionVisitor

private static class SubstitutionVisitor.TrivialRule
extends SubstitutionVisitor.AbstractUnifyRule

Implementation of SubstitutionVisitor.UnifyRule that matches if the query is already equal to the target.

Matches scans to the same table, because these will be MutableScans with the same LogicalTableScan instance.

Field Summary

Fields

Modifier and Type	Field and Description
private static SubstitutionVisitor.TrivialRule	INSTANCE

Fields inherited from class org.apache.calcite.plan.SubstitutionVisitor.UnifyRule

queryOperand, slotCount, targetOperand

Constructor Summary

Constructors

Modifier	Constructor and Description
private	TrivialRule()

Method Summary

Modifier and Type	Method and Description
SubstitutionVisitor.UnifyResult	apply(SubstitutionVisitor.UnifyRuleCall call) Applies this rule to a particular node in a query.

Methods inherited from class org.apache.calcite.plan.SubstitutionVisitor.AbstractUnifyRule

any, isValid, operand, query, target

Methods inherited from class org.apache.calcite.plan.SubstitutionVisitor.UnifyRule

copy, match

Methods inherited from class java.lang.Object

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

Field Detail

INSTANCE

private static final SubstitutionVisitor.TrivialRule INSTANCE

Constructor Detail

TrivialRule

private TrivialRule()

Method Detail

apply

public SubstitutionVisitor.UnifyResult apply(SubstitutionVisitor.UnifyRuleCall call)

Description copied from class: SubstitutionVisitor.UnifyRule

Applies this rule to a particular node in a query. The goal is to convert query into target. Before the rule is invoked, Calcite has made sure that query's children are equivalent to target's children.

There are 3 possible outcomes:

• query already exactly matches target; returns target
• query is sufficiently close to a match for target; returns target
• query cannot be made to match target; returns null

REVIEW: Is possible that we match query PLUS one or more of its ancestors?

Specified by:

apply in class SubstitutionVisitor.UnifyRule

Parameters:

call - Input parameters