org.modeshape.jcr.query.engine.process

Class JoinSequence

java.lang.Object

org.modeshape.jcr.query.NodeSequence

org.modeshape.jcr.query.engine.process.DelegatingSequence

org.modeshape.jcr.query.engine.process.BufferingSequence

org.modeshape.jcr.query.engine.process.JoinSequence

Direct Known Subclasses:

HashJoinSequence

@NotThreadSafe
public abstract class JoinSequence
extends BufferingSequence

A NodeSequence implementation that performs a join of two delegate sequences.

See Also:

HashJoinSequence

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected static interface	JoinSequence.BatchFactory A factory for batches.
protected class	JoinSequence.EmptyBatchFactory A JoinSequence.BatchFactory that always returns null.
protected class	JoinSequence.LeftOnlyBatch
protected class	JoinSequence.LeftOnlyBatchFactory A JoinSequence.BatchFactory for batches that return only the left-hand rows.
static class	JoinSequence.Range<K>
static interface	JoinSequence.RangeProducer<K>
protected class	JoinSequence.RightOnlyBatch
protected class	JoinSequence.RightOnlyBatchFactory A JoinSequence.BatchFactory for batches that return only the right-hand rows.

Nested classes/interfaces inherited from class org.modeshape.jcr.query.NodeSequence

NodeSequence.AlternateSizeBatch, NodeSequence.Batch, NodeSequence.LimitBatch, NodeSequence.MultiWidthBatch, NodeSequence.Restartable, NodeSequence.RowAccessor, NodeSequence.RowFilter, NodeSequence.SingleWidthBatch

Field Summary

Fields

Modifier and Type	Field and Description
protected int	batchSize
protected NodeSequence.Batch	currentLeft
protected JoinType	joinType
protected NodeSequence	left
protected RowExtractors.ExtractFromRow	leftExtractor
protected int	leftWidth
protected int	totalWidth

Fields inherited from class org.modeshape.jcr.query.engine.process.BufferingSequence

buffer, cache, extractor, logger, remainingRowCount, rowFactory, trace, width, workspaceName

Fields inherited from class org.modeshape.jcr.query.engine.process.DelegatingSequence

delegate

Fields inherited from class org.modeshape.jcr.query.NodeSequence

LOGGER, NO_PASS_ROW_FILTER, PASS_ROW_FILTER

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	JoinSequence(String workspaceName, NodeSequence left, NodeSequence right, RowExtractors.ExtractFromRow leftExtractor, RowExtractors.ExtractFromRow rightExtractor, JoinType joinType, BufferManager bufferMgr, CachedNodeSupplier nodeCache, boolean pack, boolean useHeap, boolean allowDuplicates)

Method Summary

Methods

Modifier and Type	Method and Description
void	close() Signal that this node sequence is no longer needed.
protected NodeSequence.Batch	findNextNonEmptyLeftBatch()
protected abstract JoinSequence.BatchFactory	initialize() Called once when the implementation is to create a JoinSequence.BatchFactory for all batches returned by this join sequence.
boolean	isEmpty() Determine whether this results is known to be empty.
NodeSequence.Batch	nextBatch() Get the next batch of NodeKey instances.
protected boolean	useAllLeftRowsWhenNoMatchingRightRows() Determine whether the algorithm that encounters a left row with no matching right rows should still include such left rows in the result.
protected boolean	useAllRightRowsWhenNoLeftRows() Determine whether the algorithm that encounters no left rows should process the right rows.
protected boolean	useNonMatchingRightRows() Determine whether the algorithm should return rows from the right-side of the join that were no matched to left rows.
int	width() Get the number of nodes in each row.

Methods inherited from class org.modeshape.jcr.query.engine.process.BufferingSequence

batchFrom, createRow, loadAll, rowCount

Methods inherited from class org.modeshape.jcr.query.engine.process.DelegatingSequence

getRowCount

Methods inherited from class org.modeshape.jcr.query.NodeSequence

append, batchFilteredWith, batchOf, batchOf, batchOf, batchOfKeys, batchOfKeys, batchOfKeys, batchOfKeys, batchWithCount, copy, emptyBatch, emptySequence, filter, keyFor, limit, limit, merging, requireBoth, requireEither, skip, slice, slicingBatch, withBatch, withBatches, withBatches, withNode, withNodeKeys, withNodeKeys, withNodeKeys, withNodeKeys, withNodes, withNodes

Methods inherited from class java.lang.Object

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

Field Detail

left

protected final NodeSequence left

leftExtractor

protected final RowExtractors.ExtractFromRow leftExtractor

leftWidth

protected final int leftWidth

totalWidth

protected final int totalWidth

joinType

protected final JoinType joinType

batchSize

protected int batchSize

currentLeft

protected NodeSequence.Batch currentLeft

Constructor Detail

JoinSequence

protected JoinSequence(String workspaceName,
            NodeSequence left,
            NodeSequence right,
            RowExtractors.ExtractFromRow leftExtractor,
            RowExtractors.ExtractFromRow rightExtractor,
            JoinType joinType,
            BufferManager bufferMgr,
            CachedNodeSupplier nodeCache,
            boolean pack,
            boolean useHeap,
            boolean allowDuplicates)

Method Detail

width

public int width()

Description copied from class: NodeSequence

Get the number of nodes in each row.

Overrides:

width in class DelegatingSequence

Returns:

the width of each row; always positive

isEmpty

public boolean isEmpty()

Description copied from class: NodeSequence

Determine whether this results is known to be empty.

Overrides:

isEmpty in class BufferingSequence

Returns:

the true if there are no results, or false if there is at least some or if the number of rows is not known

nextBatch

public NodeSequence.Batch nextBatch()

Description copied from class: NodeSequence

Get the next batch of NodeKey instances.

Overrides:

nextBatch in class DelegatingSequence

Returns:

the next batch, or null if there are no more batches.

findNextNonEmptyLeftBatch

protected NodeSequence.Batch findNextNonEmptyLeftBatch()

initialize

protected abstract JoinSequence.BatchFactory initialize()

Called once when the implementation is to create a JoinSequence.BatchFactory for all batches returned by this join sequence. This is called only when we know that there are at least some rows on the left side.

Returns:

the batch factory that should be used to obtain the batches; never null

useAllRightRowsWhenNoLeftRows

protected boolean useAllRightRowsWhenNoLeftRows()

Determine whether the algorithm that encounters no left rows should process the right rows. This method only returns true when the join type is a right outer join.

The cross join (or Cartesian Product) is not included because the number of rows returned will be Nleft x Nright, where Nleft is the number of rows on the left-hand side, and Nright is the number of rows on the right-hand side. Therefore, if either is empty, the result is empty.

Returns:

true if the right rows should be returned when there are no left rows, or false otherwise

useAllLeftRowsWhenNoMatchingRightRows

protected boolean useAllLeftRowsWhenNoMatchingRightRows()

Determine whether the algorithm that encounters a left row with no matching right rows should still include such left rows in the result. This method only returns true when the join type is a full outer join or left outer join.

Returns:

true if the left rows should be returned even when there are no matching rows on the right, or false otherwise

useNonMatchingRightRows

protected boolean useNonMatchingRightRows()

Determine whether the algorithm should return rows from the right-side of the join that were no matched to left rows. This method only returns true when the join type is a full outer join or right outer join.

Returns:

true if the join algorithm should return rows on the right that did not match rows on the left, or false otherwise

close

public void close()

Description copied from class: NodeSequence

Signal that this node sequence is no longer needed.

Overrides:

close in class BufferingSequence