Package org.apache.calcite.rel.rules

Class UnionEliminatorRule

java.lang.Object

org.apache.calcite.plan.RelOptRule

org.apache.calcite.plan.RelRule<UnionEliminatorRule.Config>

org.apache.calcite.rel.rules.UnionEliminatorRule

All Implemented Interfaces:

SubstitutionRule, TransformationRule

@Enclosing
public class UnionEliminatorRule
extends RelRule<UnionEliminatorRule.Config>
implements SubstitutionRule

UnionEliminatorRule checks to see if its possible to optimize a Union call by eliminating the Union operator altogether in the case the call consists of only one input.

Originally written for Union (hence the name), but now also applies to Intersect and Minus.

See Also:

• CoreRules.UNION_REMOVE

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	UnionEliminatorRule.Config	Rule configuration.

Nested classes/interfaces inherited from class org.apache.calcite.plan.RelRule

RelRule.Done, RelRule.MatchHandler<R extends RelOptRule>, RelRule.OperandBuilder, RelRule.OperandDetailBuilder<R extends RelNode>, RelRule.OperandTransform

Nested classes/interfaces inherited from class org.apache.calcite.plan.RelOptRule

RelOptRule.ConverterRelOptRuleOperand

Field Summary

Fields inherited from class org.apache.calcite.plan.RelRule

config

Fields inherited from class org.apache.calcite.plan.RelOptRule

description, operands, relBuilderFactory

Constructor Summary

Constructors

Modifier	Constructor	Description
	UnionEliminatorRule(Class<? extends SetOp> setOpClass, String description, RelBuilderFactory relBuilderFactory)	Deprecated.
	UnionEliminatorRule(Class<? extends Union> unionClass, RelBuilderFactory relBuilderFactory)	Deprecated.
protected	UnionEliminatorRule(UnionEliminatorRule.Config config)	Creates a UnionEliminatorRule.

Method Summary

Modifier and Type	Method	Description
boolean	autoPruneOld()	Whether the planner should automatically prune old node when there is at least 1 equivalent rel generated by the rule.
boolean	matches(RelOptRuleCall call)	Returns whether this rule could possibly match the given operands.
void	onMatch(RelOptRuleCall call)	Receives notification about a rule match.

Methods inherited from class org.apache.calcite.plan.RelOptRule

any, convert, convert, convert, convert, convertList, convertOperand, convertOperand, equals, equals, getOperand, getOperands, getOutConvention, getOutTrait, hashCode, none, operand, operand, operand, operand, operand, operandJ, operandJ, some, toString, unordered

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Details

UnionEliminatorRule

protected UnionEliminatorRule(UnionEliminatorRule.Config config)

Creates a UnionEliminatorRule.

UnionEliminatorRule

@Deprecated
public UnionEliminatorRule(Class<? extends SetOp> setOpClass,
 String description,
 RelBuilderFactory relBuilderFactory)

Deprecated.

UnionEliminatorRule

@Deprecated
public UnionEliminatorRule(Class<? extends Union> unionClass,
 RelBuilderFactory relBuilderFactory)

Deprecated.

Method Details

matches

public boolean matches(RelOptRuleCall call)

Description copied from class: RelOptRule

Returns whether this rule could possibly match the given operands.

This method is an opportunity to apply side-conditions to a rule. The RelOptPlanner calls this method after matching all operands of the rule, and before calling RelOptRule.onMatch(RelOptRuleCall).

In implementations of RelOptPlanner which may queue up a matched RelOptRuleCall for a long time before calling RelOptRule.onMatch(RelOptRuleCall), this method is beneficial because it allows the planner to discard rules earlier in the process.

The default implementation of this method returns true. It is acceptable for any implementation of this method to give a false positives, that is, to say that the rule matches the operands but have RelOptRule.onMatch(RelOptRuleCall) subsequently not generate any successors.

The following script is useful to identify rules which commonly produce no successors. You should override this method for these rules:

awk '
 /Apply rule/ {rule=$4; ruleCount[rule]++;}
 /generated 0 successors/ {ruleMiss[rule]++;}
 END {
   printf "%-30s %s %s\n", "Rule", "Fire", "Miss";
   for (i in ruleCount) {
     printf "%-30s %5d %5d\n", i, ruleCount[i], ruleMiss[i];
   }
 } ' FarragoTrace.log

Overrides:

matches in class RelOptRule

Parameters:

call - Rule call which has been determined to match all operands of this rule

Returns:

whether this RelOptRule matches a given RelOptRuleCall

onMatch

public void onMatch(RelOptRuleCall call)

Description copied from class: RelOptRule

Receives notification about a rule match. At the time that this method is called, call.rels holds the set of relational expressions which match the operands to the rule; call.rels[0] is the root expression.

Typically a rule would check that the nodes are valid matches, creates a new expression, then calls back RelOptRuleCall.transformTo(org.apache.calcite.rel.RelNode, java.util.Map<org.apache.calcite.rel.RelNode, org.apache.calcite.rel.RelNode>, org.apache.calcite.plan.RelHintsPropagator) to register the expression.

Specified by:

onMatch in class RelOptRule

Parameters:

call - Rule call

See Also:

• RelOptRule.matches(RelOptRuleCall)

autoPruneOld

public boolean autoPruneOld()

Description copied from interface: SubstitutionRule

Whether the planner should automatically prune old node when there is at least 1 equivalent rel generated by the rule.

Default is false, the user needs to prune the old node manually in the rule.

Specified by:

autoPruneOld in interface SubstitutionRule