saffron.rel
Class Join

java.lang.Object
  |
  +--saffron.rel.Rel
        |
        +--saffron.rel.Join

Direct Known Subclasses:

Correlator, JavaNestedLoopJoin, PlanNestedLoopJoin

public class Join

extends Rel

A Join represents two relational expressions joined according to some condition.

Nested Class Summary

private static class	Join.ConvertToJavaRule
private static class	Join.ConvertToPlanRule
static class	Join.JoinType Values are as JoinExpression.getJoinTypeCode(java.lang.String).

Nested classes inherited from class saffron.rel.Rel

Field Summary

protected Expression	condition
protected int	joinType Values must be of enumeration Join.JoinType, except that Join.JoinType.RIGHT is disallowed.
protected Rel	left
protected Rel	right
protected Set	variablesStopped

Fields inherited from class saffron.rel.Rel

cluster, digest, emptyArray, id, nextId, rowType

Constructor Summary

Join(Cluster cluster, Rel left, Rel right, Expression condition, int joinType, Set variablesStopped)

Method Summary

void	childrenAccept(RelVisitor visitor)
Object	clone()
protected Type	deriveRowType()
void	explain(PlanWriter pw)
Expression[]	getChildExps() Returns an array of this Rel's child expressions (not including the inputs returned by getInputs().
Expression	getCondition()
Rel[]	getInputs() Returns an array of this Rel's inputs.
int	getJoinType()
Rel	getLeft()
Rel	getRight()
Set	getVariablesStopped() Returns the names of variables which are set in this relational expression but also used and therefore not available to parents of this relational expression.
static void	register(Planner planner) See Rel.register(saffron.Planner).
void	registerStoppedVariable(String name)
void	replaceInput(int ordinalInParent, Rel p) Replaces the ordinalInParentth input.
void	setVariablesStopped(HashSet set)
int	switchJoinType(int joinType)

Methods inherited from class saffron.rel.Rel

computeDigest, computeSelfCost, getCluster, getConvention, getCorelVariable, getEnvironment, getId, getInput, getOrCreateCorelVariable, getParentEnv, getQualifier, getQuery, getRelTypeName, getRows, getRowType, getTable, getType, implement, implementExp, implementExps, implementFieldAccess, implementSelf, isAccessTo, isDistinct, onRegister, recomputeDigest, registerCorelVariable, setCorelVariable, toString

Methods inherited from class java.lang.Object

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

Field Detail

left

protected Rel left

right

protected Rel right

condition

protected Expression condition

variablesStopped

protected Set variablesStopped

joinType

protected int joinType

Values must be of enumeration Join.JoinType, except that Join.JoinType.RIGHT is disallowed.

Constructor Detail

Join

public Join(Cluster cluster,
            Rel left,
            Rel right,
            Expression condition,
            int joinType,
            Set variablesStopped)

Method Detail

clone

public Object clone()

Specified by:

clone in class Rel

getLeft

public Rel getLeft()

getRight

public Rel getRight()

getCondition

public Expression getCondition()

getJoinType

public int getJoinType()

getInputs

public Rel[] getInputs()

Description copied from class: Rel

Returns an array of this Rel's inputs. If there are no inputs, returns an empty array, not null.

Overrides:

getInputs in class Rel

getChildExps

public Expression[] getChildExps()

Description copied from class: Rel

Returns an array of this Rel's child expressions (not including the inputs returned by Rel.getInputs(). If there are no child expressions, returns an empty array, not null.

Overrides:

getChildExps in class Rel

replaceInput

public void replaceInput(int ordinalInParent,
                         Rel p)

Description copied from class: Rel

Replaces the ordinalInParent^th input. You must override this method if you override Rel.getInputs().

Overrides:

replaceInput in class Rel

childrenAccept

public void childrenAccept(RelVisitor visitor)

Overrides:

childrenAccept in class Rel

deriveRowType

protected Type deriveRowType()

Specified by:

deriveRowType in class Rel

getVariablesStopped

public Set getVariablesStopped()

Description copied from class: Rel

Returns the names of variables which are set in this relational expression but also used and therefore not available to parents of this relational expression.

By default, returns the empty set. Derived classes may override this method.

Overrides:

getVariablesStopped in class Rel

setVariablesStopped

public void setVariablesStopped(HashSet set)

registerStoppedVariable

public void registerStoppedVariable(String name)

register

public static void register(Planner planner)

See Rel.register(saffron.Planner).

explain

public void explain(PlanWriter pw)

Overrides:

explain in class Rel

switchJoinType

public int switchJoinType(int joinType)