org.apache.calcite.rel.rules

Class JoinToMultiJoinRule

java.lang.Object

org.apache.calcite.plan.RelOptRule

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

org.apache.calcite.rel.rules.JoinToMultiJoinRule

All Implemented Interfaces:

TransformationRule

@Value.Enclosing
public class JoinToMultiJoinRule
extends RelRule<JoinToMultiJoinRule.Config>
implements TransformationRule

Planner rule to flatten a tree of LogicalJoins into a single MultiJoin with N inputs.

An input is not flattened if the input is a null generating input in an outer join, i.e., either input in a full outer join, the right hand side of a left outer join, or the left hand side of a right outer join.

Join conditions are also pulled up from the inputs into the topmost MultiJoin, unless the input corresponds to a null generating input in an outer join,

Outer join information is also stored in the MultiJoin. A boolean flag indicates if the join is a full outer join, and in the case of left and right outer joins, the join type and outer join conditions are stored in arrays in the MultiJoin. This outer join information is associated with the null generating input in the outer join. So, in the case of a a left outer join between A and B, the information is associated with B, not A.

Here are examples of the MultiJoins constructed after this rule has been applied on following join trees.

• A JOIN B → MJ(A, B)
• A JOIN B JOIN C → MJ(A, B, C)
• A LEFT JOIN B → MJ(A, B), left outer join on input#1
• A RIGHT JOIN B → MJ(A, B), right outer join on input#0
• A FULL JOIN B → MJ[full](A, B)
• A LEFT JOIN (B JOIN C) → MJ(A, MJ(B, C))), left outer join on input#1 in the outermost MultiJoin
• (A JOIN B) LEFT JOIN C → MJ(A, B, C), left outer join on input#2
• (A LEFT JOIN B) JOIN C → MJ(MJ(A, B), C), left outer join on input#1 of the inner MultiJoin TODO
• A LEFT JOIN (B FULL JOIN C) → MJ(A, MJ[full](B, C)), left outer join on input#1 in the outermost MultiJoin
• (A LEFT JOIN B) FULL JOIN (C RIGHT JOIN D) → MJ[full](MJ(A, B), MJ(C, D)), left outer join on input #1 in the first inner MultiJoin and right outer join on input#0 in the second inner MultiJoin

The constructor is parameterized to allow any sub-class of Join, not just LogicalJoin.

See Also:

FilterMultiJoinMergeRule, ProjectMultiJoinMergeRule, CoreRules.JOIN_TO_MULTI_JOIN

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	JoinToMultiJoinRule.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 and Description
	JoinToMultiJoinRule(Class<? extends Join> clazz) Deprecated.
	JoinToMultiJoinRule(Class<? extends Join> joinClass, RelBuilderFactory relBuilderFactory) Deprecated.
protected	JoinToMultiJoinRule(JoinToMultiJoinRule.Config config) Creates a JoinToMultiJoinRule.

Method Summary

Modifier and Type	Method and Description
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, 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 Detail

JoinToMultiJoinRule

protected JoinToMultiJoinRule(JoinToMultiJoinRule.Config config)

Creates a JoinToMultiJoinRule.

JoinToMultiJoinRule

@Deprecated
public JoinToMultiJoinRule(Class<? extends Join> clazz)

Deprecated.

JoinToMultiJoinRule

@Deprecated
public JoinToMultiJoinRule(Class<? extends Join> joinClass,
                                       RelBuilderFactory relBuilderFactory)

Deprecated.

Method Detail

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)