org.apache.calcite.rel.rules

Class LoptSemiJoinOptimizer

java.lang.Object

org.apache.calcite.rel.rules.LoptSemiJoinOptimizer

public class LoptSemiJoinOptimizer
extends Object

Implements the logic for determining the optimal semi-joins to be used in processing joins in a query.

Constructor Summary

Constructors

Constructor and Description
LoptSemiJoinOptimizer(RelMetadataQuery mq, LoptMultiJoin multiJoin, RexBuilder rexBuilder)

Method Summary

Modifier and Type	Method and Description
boolean	chooseBestSemiJoin(LoptMultiJoin multiJoin) Finds the optimal semijoin for filtering the least costly fact table from among the remaining possible semijoins to choose from.
RelNode	getChosenSemiJoin(int factIdx) Returns the optimal semijoin for the specified factor; may be the factor itself if semijoins are not chosen for the factor.
void	makePossibleSemiJoins(LoptMultiJoin multiJoin) Determines all possible semijoins that can be used by dimension tables to filter fact tables.

Methods inherited from class java.lang.Object

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

Constructor Detail

LoptSemiJoinOptimizer

public LoptSemiJoinOptimizer(RelMetadataQuery mq,
                             LoptMultiJoin multiJoin,
                             RexBuilder rexBuilder)

Method Detail

makePossibleSemiJoins

public void makePossibleSemiJoins(LoptMultiJoin multiJoin)

Determines all possible semijoins that can be used by dimension tables to filter fact tables. Constructs SemiJoinRels corresponding to potential dimension table filters and stores them in the member field "possibleSemiJoins"

Parameters:

multiJoin - join factors being optimized

chooseBestSemiJoin

public boolean chooseBestSemiJoin(LoptMultiJoin multiJoin)

Finds the optimal semijoin for filtering the least costly fact table from among the remaining possible semijoins to choose from. The chosen semijoin is stored in the chosenSemiJoins array

Parameters:

multiJoin - join factors being optimized

Returns:

true if a suitable semijoin is found; false otherwise

getChosenSemiJoin

public RelNode getChosenSemiJoin(int factIdx)

Returns the optimal semijoin for the specified factor; may be the factor itself if semijoins are not chosen for the factor.

Parameters:

factIdx - Index corresponding to the desired factor