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org.modeshape.jcr.query.engine.process.HashJoinSequence Maven / Gradle / Ivy
/*
* ModeShape (http://www.modeshape.org)
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.modeshape.jcr.query.engine.process;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import org.mapdb.Serializer;
import org.modeshape.common.annotation.NotThreadSafe;
import org.modeshape.common.collection.MultiIterator;
import org.modeshape.common.collection.SequentialIterator;
import org.modeshape.jcr.cache.CachedNode;
import org.modeshape.jcr.cache.CachedNodeSupplier;
import org.modeshape.jcr.query.BufferManager;
import org.modeshape.jcr.query.BufferManager.DistinctBuffer;
import org.modeshape.jcr.query.NodeSequence;
import org.modeshape.jcr.query.RowExtractors.ExtractFromRow;
import org.modeshape.jcr.query.engine.process.BufferedRows.BufferedRow;
import org.modeshape.jcr.query.model.JoinType;
import org.modeshape.jcr.query.model.TypeSystem.TypeFactory;
/**
* A {@link NodeSequence} implementation that performs an equijoin of two delegate sequences. The hash-join algorithm loads all
* values on the right side into a buffer that hashes the right join condition value of each row. Then, it iterates through all
* tuples on the left side and finds which of the values on the right have a matching join condition value.
*
* @author Randall Hauch ([email protected] )
*/
@NotThreadSafe
public class HashJoinSequence extends JoinSequence {
protected final DistinctBuffer rightMatchedRowKeys;
protected final DistinctBuffer rightRowsWithNullKey;
protected final RangeProducer rangeProducer;
@SuppressWarnings( "unchecked" )
public HashJoinSequence( String workspaceName,
NodeSequence left,
NodeSequence right,
ExtractFromRow leftExtractor,
ExtractFromRow rightExtractor,
JoinType joinType,
BufferManager bufferMgr,
CachedNodeSupplier nodeCache,
RangeProducer rangeProducer,
boolean pack,
boolean useHeap ) {
super(workspaceName, left, right, leftExtractor, rightExtractor, joinType, bufferMgr, nodeCache, pack, useHeap, true);
this.rangeProducer = (RangeProducer)rangeProducer;
if (useNonMatchingRightRows()) {
TypeFactory keyType = rightExtractor.getType();
Serializer keySerializer = bufferMgr.serializerFor(keyType);
rightMatchedRowKeys = (DistinctBuffer)bufferMgr.createDistinctBuffer(keySerializer).keepSize(true)
.useHeap(useHeap).make();
Serializer rowSerializer = (Serializer)BufferedRows.serializer(nodeCache, width);
rightRowsWithNullKey = bufferMgr.createDistinctBuffer(rowSerializer).keepSize(true).useHeap(useHeap).make();
} else {
rightMatchedRowKeys = null;
rightRowsWithNullKey = null;
}
}
@Override
protected BatchFactory initialize() {
// Load all of the right sequence into the buffer ...
int firstBatchSize = loadAll(delegate, extractor, rightRowsWithNullKey);
if (firstBatchSize == 0) {
// No rows were found on the right, so see if we need to return any nodes ...
switch (joinType) {
case CROSS:
case RIGHT_OUTER:
// Nothing on the right, so return no rows ...
return new EmptyBatchFactory();
case FULL_OUTER:
case LEFT_OUTER:
// Nothing on the right but something on the left, so ...
return new LeftOnlyBatchFactory();
case INNER:
// Nothing on the right, that means no left rows will match ...
return new EmptyBatchFactory();
}
}
// Otherwise, there are rows on the left and the right ...
switch (joinType) {
case CROSS:
// We use all of the rows on the right for every row on the left; logic is a little different ...
return new HashCrossJoinBatchFactory();
case RIGHT_OUTER:
case FULL_OUTER:
case LEFT_OUTER:
case INNER:
default:
// We always try to match left and right rows, but possibly also include unmatched right rows ...
return rangeProducer != null ? new HashJoinRangeBatchFactory() : new HashJoinBatchFactory();
}
}
protected Iterator allRightRows() {
if (rightRowsWithNullKey != null) {
return SequentialIterator.create(rightRowsWithNullKey.iterator(), buffer.ascending());
}
return buffer.ascending();
}
@Override
public void close() {
try {
super.close();
} finally {
try {
if (rightMatchedRowKeys != null) {
rightMatchedRowKeys.close();
}
} finally {
if (rightRowsWithNullKey != null) {
rightRowsWithNullKey.close();
}
}
}
}
@Override
public String toString() {
return "(hash-join width=" + width() + " " + joinType + " left=" + left + ", right=" + delegate + ", on " + leftExtractor
+ "=" + extractor + " )";
}
protected class HashJoinBatchFactory implements BatchFactory {
private Iterator rightRows;
@Override
public Batch nextBatch() {
Batch leftBatch = findNextNonEmptyLeftBatch();
if (leftBatch != null) {
currentLeft = null; // reset ...
return createBatch(leftBatch);
}
// Otherwise, we're done with the left side ...
if (rightMatchedRowKeys == null) {
// We never need to return any unused/unmatched rows from the right, so we're done ...
return null;
}
if (rightRows == null) {
// This is the first batch with the unused right rows, so get the iterator ...
rightRows = allRightRows();
}
if (!rightRows.hasNext()) return null; // we're done!
return new RightRowsBatch(rightRows, 100);
}
protected Batch createBatch( Batch leftBatch ) {
return new HashJoinBatch(leftBatch);
}
}
/**
* A batch that contains rows that will have a left value and a right value.
*
* @author Randall Hauch ([email protected] )
*/
protected class HashJoinBatch implements Batch {
private final Batch currentLeft;
private Iterator rightMatchingRows;
private BufferedRow currentRight;
protected HashJoinBatch( Batch currentLeft ) {
this.currentLeft = currentLeft;
assert this.currentLeft != null;
}
@Override
public int width() {
return totalWidth;
}
@Override
public String getWorkspaceName() {
return workspaceName;
}
@Override
public boolean isEmpty() {
return false;
}
@Override
public long rowCount() {
return -1; // don't really know how many ...
}
@Override
public boolean hasNext() {
if (rightMatchingRows != null && rightMatchingRows.hasNext()) {
// There are more rows on the right that match the current left row ...
return true;
}
if (!currentLeft.hasNext()) {
// No more left rows in this batch ...
return false;
}
// Advanced to the next left row and find the matching rows on the right ...
while (currentLeft.hasNext()) {
currentLeft.nextRow();
Object matchingValue = leftExtractor.getValueInRow(currentLeft);
rightMatchingRows = getAllRightRowsFor(matchingValue);
if (rightMatchingRows != null && rightMatchingRows.hasNext()) {
// Found a match which will be recorded when we go through the right matching rows...
return true;
}
// Did not find any matching rows on the right ...
if (useAllLeftRowsWhenNoMatchingRightRows()) {
// We still have to include the left row ...
rightMatchingRows = null;
return true;
}
// Otherwise, we don't include the left row without matching rows on the right, so find the next left row ...
}
// No more left rows ...
return false;
}
private Iterator getAllRightRowsFor( Object leftValue ) {
if (leftValue instanceof Object[]) {
// There are multiple left-hand values, so we have to look for each one ...
List> iterators = new LinkedList<>();
for (Object left : (Object[])leftValue) {
Iterator matching = getRightRowsFor(left);
if (matching != null && matching.hasNext()) {
iterators.add(matching);
}
}
if (iterators.isEmpty()) return null;
if (iterators.size() == 1) return iterators.get(0);
return MultiIterator.fromIterators(iterators);
}
// This is just a single value or even null
return getRightRowsFor(leftValue);
}
protected Iterator getRightRowsFor( Object leftValue ) {
return buffer.getAll(leftValue);
}
protected void recordRightRowsMatched( Object rightKey ) {
if (rightMatchedRowKeys != null) {
// We only record the non-null values, since NULL never matches and they will always be unmatched ...
// logger.trace("Join found matching rows on right with value {0}", matchingValue);
rightMatchedRowKeys.addIfAbsent(rightKey);
}
}
@Override
public void nextRow() {
// This current presumes that 'hasNext' was called and that either 'rightMatchingRows' is null (because there
// was no match (e.g., left outer join) or that it is non-null and has at least one value ...
if (rightMatchingRows != null) {
currentRight = rightMatchingRows.next();
// since there might be multiple rows on the right, we need to make sure we record each one
recordRightRowsMatched(extractor.getValueInRow(currentRight));
} else {
currentRight = null;
}
}
@Override
public CachedNode getNode() {
return currentLeft.getNode();
}
@Override
public CachedNode getNode( int index ) {
if (index < leftWidth) {
return currentLeft.getNode(index);
}
if (currentRight == null) return null;
return currentRight.getNode(index - leftWidth);
}
@Override
public float getScore() {
return currentLeft.getScore();
}
@Override
public float getScore( int index ) {
if (index < leftWidth) {
return currentLeft.getScore(index);
}
if (currentRight == null) return 0.0f;
return currentRight.getScore(index - leftWidth);
}
}
protected class HashJoinRangeBatchFactory extends HashJoinBatchFactory {
@Override
protected Batch createBatch( Batch leftBatch ) {
return new HashJoinRangeBatch(leftBatch);
}
}
/**
* A batch that contains rows that will have a left value and a right value.
*
* @author Randall Hauch ([email protected] )
*/
protected class HashJoinRangeBatch extends HashJoinBatch {
protected HashJoinRangeBatch( Batch currentLeft ) {
super(currentLeft);
assert HashJoinSequence.this.rangeProducer != null;
}
@Override
protected Iterator getRightRowsFor( Object leftValue ) {
if (leftValue == null) {
// Nothing on the right ever matches a NULL on the left ...
return null;
}
Range range = HashJoinSequence.this.rangeProducer.getRange(leftValue);
if (range == null) return null;
return buffer.getAll(range.lowerBound(), range.isLowerBoundIncluded(), range.upperBound(),
range.isUpperBoundIncluded());
}
}
/**
* A batch that contains rows that will have no left value and a right value. Every value on the left matches all values on
* the right, since this is a cross-join.
*
* @author Randall Hauch ([email protected] )
*/
protected class HashCrossJoinBatch extends HashJoinBatch {
protected HashCrossJoinBatch( Batch currentLeft ) {
super(currentLeft);
}
@Override
protected Iterator getRightRowsFor( Object leftValue ) {
return allRightRows();
}
@Override
protected void recordRightRowsMatched( Object rightKey ) {
// do nothing
}
}
protected class HashCrossJoinBatchFactory extends HashJoinBatchFactory {
@Override
protected Batch createBatch( Batch leftBatch ) {
return new HashCrossJoinBatch(leftBatch);
}
}
/**
* A batch that contains rows that will have no left value and a right value.
*
* @author Randall Hauch ([email protected] )
*/
protected class RightRowsBatch implements Batch {
private final Iterator rightRows;
private final int maxSize;
private BufferedRow currentRight;
private int count = 0;
protected RightRowsBatch( Iterator rightRows,
int maxSize ) {
this.rightRows = rightRows;
this.maxSize = maxSize;
assert this.rightRows != null;
assert this.maxSize > 0;
}
@Override
public int width() {
return totalWidth;
}
@Override
public String getWorkspaceName() {
return workspaceName;
}
@Override
public boolean isEmpty() {
return false;
}
@Override
public long rowCount() {
return -1; // don't really know how many ...
}
@Override
public boolean hasNext() {
// Find the next buffered row that was not used ...
while (rightRows.hasNext() && count < maxSize) {
currentRight = rightRows.next();
Object key = extractor.getValueInRow(currentRight);
if (key == null || rightMatchedRowKeys.addIfAbsent(key)) {
logger.trace("Join found non-matched rows on right with value {0}", key);
++count;
return true;
}
logger.trace("Join found matched rows on right with value {0}", key);
}
return false;
}
@Override
public void nextRow() {
// This currently presumes that 'hasNext' was called and that 'currentRight' has a value ...
}
@Override
public CachedNode getNode() {
// We're only returning right values, so there is never a value at index 0 ...
return null;
}
@Override
public CachedNode getNode( int index ) {
if (currentRight != null && index >= leftWidth) {
return currentRight.getNode(index - leftWidth);
}
return null;
}
@Override
public float getScore() {
// We're only returning right values, so there is never a value at index 0 ...
return 0.0f;
}
@Override
public float getScore( int index ) {
if (currentRight != null && index >= leftWidth) {
return currentRight.getScore(index - leftWidth);
}
return 0.0f;
}
}
}
