org.eigenbase.rel.rules
Class SemiJoinRel

java.lang.Object
  org.eigenbase.rel.AbstractRelNode
      org.eigenbase.rel.JoinRelBase
          org.eigenbase.rel.rules.SemiJoinRel

All Implemented Interfaces:

Cloneable, RelNode

public final class SemiJoinRel
extends JoinRelBase

A SemiJoinRel represents two relational expressions joined according to some condition, where the output only contains the columns from the left join input.

Version:

$Id: //open/dev/farrago/src/org/eigenbase/rel/rules/SemiJoinRel.java#10 $

Author:

Zelaine Fong

Field Summary

private List<Integer>	leftKeys
private List<Integer>	rightKeys

Fields inherited from class org.eigenbase.rel.JoinRelBase

condition, joinType, left, right, variablesStopped

Fields inherited from class org.eigenbase.rel.AbstractRelNode

digest, id, rowType, traits

Fields inherited from interface org.eigenbase.rel.RelNode

emptyArray

Constructor Summary

SemiJoinRel(RelOptCluster cluster, RelNode left, RelNode right, RexNode condition, List<Integer> leftKeys, List<Integer> rightKeys)

Method Summary

SemiJoinRel	clone() Clones this RelNode.
RelOptCost	computeSelfCost(RelOptPlanner planner) Returns the cost of this plan (not including children).
RelDataType	deriveRowType()
List<Integer>	getLeftKeys()
List<Integer>	getRightKeys()
double	getRows() Returns an estimate of the number of rows this relational expression will return.

Methods inherited from class org.eigenbase.rel.JoinRelBase

_isValid, childrenAccept, createJoinType, deriveJoinRowType, estimateJoinedRows, explain, getChildExps, getCondition, getInputs, getJoinType, getLeft, getRight, getSystemFieldList, getVariablesStopped, registerStoppedVariable, replaceInput, setVariablesStopped

Methods inherited from class org.eigenbase.rel.AbstractRelNode

cloneTraits, collectVariablesSet, collectVariablesUsed, computeDigest, getCluster, getCollationList, getConvention, getCorrelVariable, getDescription, getDigest, getExpectedInputRowType, getId, getInput, getOrCreateCorrelVariable, getQuery, getRelTypeName, getRowType, getTable, getTraits, inheritTraitsFrom, isAccessTo, isDistinct, isValid, onRegister, recomputeDigest, register, registerCorrelVariable, setCorrelVariable, toString

Methods inherited from class java.lang.Object

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

Field Detail

leftKeys

private List<Integer> leftKeys

rightKeys

private List<Integer> rightKeys

Constructor Detail

SemiJoinRel

public SemiJoinRel(RelOptCluster cluster,
                   RelNode left,
                   RelNode right,
                   RexNode condition,
                   List<Integer> leftKeys,
                   List<Integer> rightKeys)

Parameters:

cluster - cluster that join belongs to

left - left join input

right - right join input

condition - join condition

leftKeys - left keys of the semijoin

rightKeys - right keys of the semijoin

Method Detail

clone

public SemiJoinRel clone()

Description copied from interface: RelNode

Clones this RelNode.

Traits of the RelNode must be explicitly cloned, using AbstractRelNode.inheritTraitsFrom(AbstractRelNode), as the RelNode may have traits of which it has no knowledge. Example implementation:

     public MyRelNode clone()
     {
         MyRelNode clone = new MyRelNode(...);
         clone.inheritTraitsFrom(this);
         return clone;
     }
 

N.B.: This method must be overridden whenever an existing, concrete RelNode is extended. Otherwise, calling clone() will produce a differently typed RelNode, resulting in invalid or incorrect query plans.

Specified by:

clone in interface RelNode

Specified by:

clone in class AbstractRelNode

Returns:

a clone of this RelNode

computeSelfCost

public RelOptCost computeSelfCost(RelOptPlanner planner)

Description copied from interface: RelNode

Returns the cost of this plan (not including children). The base implementation throws an error; derived classes should override.

NOTE jvs 29-Mar-2006: Don't call this method directly. Instead, use RelMetadataQuery.getNonCumulativeCost(org.eigenbase.rel.RelNode), which gives plugins a chance to override the rel's default ideas about cost.

Specified by:

computeSelfCost in interface RelNode

Overrides:

computeSelfCost in class JoinRelBase

getRows

public double getRows()

Description copied from interface: RelNode

Returns an estimate of the number of rows this relational expression will return.

NOTE jvs 29-Mar-2006: Don't call this method directly. Instead, use RelMetadataQuery.getRowCount(org.eigenbase.rel.RelNode), which gives plugins a chance to override the rel's default ideas about row count.

Specified by:

getRows in interface RelNode

Overrides:

getRows in class JoinRelBase

deriveRowType

public RelDataType deriveRowType()

Overrides:

deriveRowType in class JoinRelBase

Returns:

returns rowtype representing only the left join input

getLeftKeys

public List<Integer> getLeftKeys()

getRightKeys

public List<Integer> getRightKeys()