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https://issues.apache.org/jira/browse/DRILL-505?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13971667#comment-13971667
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ASF GitHub Bot commented on DRILL-505:
--------------------------------------
Github user amansinha100 commented on a diff in the pull request:
https://github.com/apache/incubator-drill/pull/49#discussion_r11695140
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/join/HashJoinBatch.java
---
@@ -0,0 +1,519 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you 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.apache.drill.exec.physical.impl.join;
+
+import org.eigenbase.rel.JoinRelType;
+
+import java.io.IOException;
+import java.util.LinkedList;
+
+import com.sun.codemodel.JExpression;
+import com.sun.codemodel.JVar;
+import com.sun.codemodel.JExpr;
+
+import org.apache.drill.exec.compile.sig.GeneratorMapping;
+import org.apache.drill.exec.compile.sig.MappingSet;
+import org.apache.drill.exec.exception.ClassTransformationException;
+import org.apache.drill.exec.exception.SchemaChangeException;
+import org.apache.drill.exec.expr.ClassGenerator;
+import org.apache.drill.exec.expr.CodeGenerator;
+import org.apache.drill.exec.expr.TypeHelper;
+import org.apache.drill.exec.expr.holders.IntHolder;
+import org.apache.drill.exec.ops.FragmentContext;
+import org.apache.drill.exec.physical.config.HashJoinPOP;
+import org.apache.drill.exec.physical.impl.common.ChainedHashTable;
+import org.apache.drill.exec.physical.impl.common.HashTable;
+import org.apache.drill.exec.physical.impl.common.HashTableConfig;
+import org.apache.drill.exec.physical.impl.sort.RecordBatchData;
+import org.apache.drill.exec.physical.impl.svremover.RemovingRecordBatch;
+import org.apache.drill.exec.record.RecordBatch;
+import org.apache.drill.exec.record.AbstractRecordBatch;
+import org.apache.drill.exec.record.ExpandableHyperContainer;
+import org.apache.drill.exec.record.BatchSchema;
+import org.apache.drill.exec.record.VectorWrapper;
+import org.apache.drill.exec.record.TypedFieldId;
+import org.apache.drill.exec.vector.ValueVector;
+import org.apache.drill.exec.vector.allocator.VectorAllocator;
+
+public class HashJoinBatch extends AbstractRecordBatch<HashJoinPOP> {
+ // Probe side record batch
+ private final RecordBatch left;
+
+ // Build side record batch
+ private final RecordBatch right;
+
+ // Join type, INNER, LEFT, RIGHT or OUTER
+ private final JoinRelType joinType;
+
+ // hash table configuration, created in HashJoinPOP
+ private HashTableConfig htConfig;
+
+ // Runtime generated class implementing HashJoin interface
+ private HashJoin hashJoin = null;
+
+ /* Helper class
+ * Maintains linked list of build side records with the same key
+ * Keeps information about which build records have a corresponding
+ * matching key in the probe side (for outer, right joins)
+ */
+ private HashJoinHelper hjHelper = null;
+
+ // Underlying hashtable used by the hash join
+ private HashTable hashTable = null;
+
+ /* Hyper container to store all build side record batches.
+ * Records are retrieved from this container when there is a matching
record
+ * on the probe side
+ */
+ private ExpandableHyperContainer hyperContainer;
+
+ // Number of records to process on the probe side
+ private int recordsToProcess;
+
+ // Number of records processed on the probe side
+ private int recordsProcessed;
+
+ // Number of records in the output container
+ private int outputRecords;
+
+ // Current batch index on the build side
+ private int buildBatchIndex = 0;
+
+ // Indicate if we should drain the next record from the probe side
+ private boolean getNextRecord = true;
+
+ // Contains both batch idx and record idx of the matching record in
the build side
+ private int currentCompositeIdx = -1;
+
+ // Current state the hash join algorithm is in
+ private HashJoinState hjState = HashJoinState.BUILD;
+
+ // For outer or right joins, this is a list of unmatched records that
needs to be projected
+ private LinkedList<Integer> unmatchedBuildIndexes = null;
+
+ // List of vector allocators
+ private LinkedList<VectorAllocator> allocators = null;
+
+ // Schema of the build side
+ private BatchSchema rightSchema = null;
+
+ // Generator mapping for the build side
+ private static final GeneratorMapping PROJECT_BUILD =
GeneratorMapping.create("doSetup"/* setup method */,
+
"projectBuildRecord" /* eval method */,
+
null /* reset */, null /* cleanup */);
+
+ // Generator mapping for the probe side
+ private static final GeneratorMapping PROJECT_PROBE =
GeneratorMapping.create("doSetup" /* setup method */,
+
"projectProbeRecord" /* eval method */,
+
null /* reset */, null /* cleanup */);
+
+ // Mapping set for the build side
+ private final MappingSet projectBuildMapping = new
MappingSet("buildIndex" /* read index */, "outIndex" /* write index */,
+
"buildBatch" /* read container */,
+
"outgoing" /* write container */,
+
PROJECT_BUILD, PROJECT_BUILD);
+
+ // Mapping set for the probe side
+ private final MappingSet projectProbeMapping = new
MappingSet("probeIndex" /* read index */, "outIndex" /* write index */,
+
"probeBatch" /* read container */,
+
"outgoing" /* write container */,
+
PROJECT_PROBE, PROJECT_PROBE);
+
+ // Possible states for the hash join
+ public static enum HashJoinState {
+ BUILD, // Build phase, go through the 'right' record batches and
create the hash table
+ PROBE, // Go through the 'left' record batches, probe the hash
table project the records if the key matches
+ PROJECT_RIGHT, // If its a RIGHT OUTER or FULL join go through the
build records that didn't match a probe record and project them
+ DONE // Done processing all records get out
+ }
+
+ @Override
+ public int getRecordCount() {
+ return outputRecords;
+ }
+
+
+ @Override
+ public IterOutcome next() {
+
+ IterOutcome leftUpstream = IterOutcome.NONE;
+
+ try {
+
+ if (hjState == HashJoinState.BUILD) {
+
+ // Initialize the hash join helper context
+ hjHelper = new HashJoinHelper(context);
+
+ /* Build phase requires setting up the hash table. Hash
table will
+ * materialize both the build and probe side expressions
while
+ * creating the hash table. So we need to invoke next() on
our probe batch
+ * as well, for the materialization to be successful. This
batch will not be used
+ * till we complete the build phase.
+ */
+ left.next();
--- End diff --
Does calling next() on the left (probe) side while we are in the build
phase only need to be done once when we are starting the build phase ? Once we
have the probe side expression for materialization, as long as the schema does
not change, we don't need to call next() again on the left side I think. We
should also think about whether there is an alternative way that maybe gives
access to the expressions on the build side without the need to fetch the rows.
> Implement hash join
> -------------------
>
> Key: DRILL-505
> URL: https://issues.apache.org/jira/browse/DRILL-505
> Project: Apache Drill
> Issue Type: New Feature
> Reporter: Mehant Baid
> Assignee: Mehant Baid
> Attachments: DRILL-505.patch
>
>
> Implement the hash join operator. The first version of the hash join
> algorithm is a simple in memory implementation only and will not spill to
> disk
> Scope is to support inner, left outer, right outer and full outer joins for
> simple equality conditions.
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