org.axiondb.engine.rowiterators

Class NestedLoopJoinedRowIterator

java.lang.Object

org.axiondb.engine.rowiterators.BaseRowIterator

org.axiondb.engine.rowiterators.AbstractJoinedRowIterator

org.axiondb.engine.rowiterators.NestedLoopJoinedRowIterator

All Implemented Interfaces:

RowIterator

public class NestedLoopJoinedRowIterator
extends AbstractJoinedRowIterator

A Nested Loop Join is performed by doing a scan over the left subtree and for each row in it performing a full scan of the right subtree. This is the default join algorithm, which can be used for any join. However, it is usually less efficient than the other methods. Usually, either an existing index, or a dynamic index, used in an ANL join, will cost much less. Occasionally, when subtree cardinalities are very low (possibly because of index bracketing), nested loop will be the method with the least cost.

Version:

$Revision: 1.7 $ $Date: 2005/04/02 18:23:30 $

Constructor Summary

Constructors

Constructor and Description
NestedLoopJoinedRowIterator(RowIterator left, RowIterator right, int rightColumnCount)
NestedLoopJoinedRowIterator(RowIterator left, RowIterator right, int rightColumnCount, boolean rightOuter, boolean swapLeftAndRight)

Method Summary

Modifier and Type	Method and Description
protected RowIterator	generateRightRowIterator()
void	reset() Re-initialize this RowIterator to its initial state (positioned just before the first Rowin the list).
java.lang.String	toString()

Methods inherited from class org.axiondb.engine.rowiterators.AbstractJoinedRowIterator

current, currentIndex, getJoinCondition, getLeftRowIterator, getRightSideColumnCount, getRowDecorator, hasCurrent, hasNext, hasPrevious, isRightOuter, isSwapLeftAndRight, next, nextIndex, previous, previousIndex, setJoinCondition, setLeftRowIterator, setRightOuter, setRightSideColumnCount, setSwapLeftAndRight

Methods inherited from class org.axiondb.engine.rowiterators.BaseRowIterator

add, first, isEmpty, last, next, peekNext, peekPrevious, previous, remove, set, size

Methods inherited from class java.lang.Object

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

Constructor Detail

NestedLoopJoinedRowIterator

public NestedLoopJoinedRowIterator(RowIterator left,
                                   RowIterator right,
                                   int rightColumnCount,
                                   boolean rightOuter,
                                   boolean swapLeftAndRight)
                            throws AxionException

Throws:

AxionException

NestedLoopJoinedRowIterator

public NestedLoopJoinedRowIterator(RowIterator left,
                                   RowIterator right,
                                   int rightColumnCount)
                            throws AxionException

Throws:

AxionException

Method Detail

generateRightRowIterator

protected RowIterator generateRightRowIterator()
                                        throws AxionException

Specified by:

generateRightRowIterator in class AbstractJoinedRowIterator

Throws:

AxionException

reset

public void reset()
           throws AxionException

Description copied from interface: RowIterator

Re-initialize this RowIterator to its initial state (positioned just before the first Rowin the list).

Specified by:

reset in interface RowIterator

Overrides:

reset in class AbstractJoinedRowIterator

Throws:

AxionException

toString

public java.lang.String toString()

Overrides:

toString in class AbstractJoinedRowIterator