org.apache.calcite.rel.rules

Class JoinCommuteRule

java.lang.Object

org.apache.calcite.plan.RelOptRule

org.apache.calcite.rel.rules.JoinCommuteRule

public class JoinCommuteRule
extends RelOptRule

Planner rule that permutes the inputs to a Join.

Outer joins cannot be permuted.

To preserve the order of columns in the output row, the rule adds a Project.

Field Summary

Fields

Modifier and Type	Field and Description
static JoinCommuteRule	INSTANCE The singleton.

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

description, operands

Constructor Summary

Constructors

Constructor and Description
JoinCommuteRule(Class<? extends Join> clazz, RelFactories.ProjectFactory projectFactory)

Method Summary

Methods

Modifier and Type	Method and Description
void	onMatch(RelOptRuleCall call) Receives notification about a rule match.
static RelNode	swap(Join join) Returns a relational expression with the inputs switched round.
static RelNode	swap(Join join, boolean swapOuterJoins)

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

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

Methods inherited from class java.lang.Object

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

Field Detail

INSTANCE

public static final JoinCommuteRule INSTANCE

The singleton.

Constructor Detail

JoinCommuteRule

public JoinCommuteRule(Class<? extends Join> clazz,
               RelFactories.ProjectFactory projectFactory)

Method Detail

swap

public static RelNode swap(Join join)

Returns a relational expression with the inputs switched round. Does not modify join. Returns null if the join cannot be swapped (for example, because it is an outer join).

swap

public static RelNode swap(Join join,
           boolean swapOuterJoins)

Parameters:

join - join to be swapped

swapOuterJoins - whether outer joins should be swapped

Returns:

swapped join if swapping possible; else null

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>) to register the expression.

Specified by:

onMatch in class RelOptRule

Parameters:

call - Rule call

See Also:

RelOptRule.matches(RelOptRuleCall)