com.bigdata.bop.join.JVMHashJoinOp Maven / Gradle / Ivy
/**
Copyright (C) SYSTAP, LLC DBA Blazegraph 2006-2016. All rights reserved.
Contact:
SYSTAP, LLC DBA Blazegraph
2501 Calvert ST NW #106
Washington, DC 20008
[email protected]
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/*
* Created on Aug 14, 2011
*/
package com.bigdata.bop.join;
import java.util.Map;
import com.bigdata.bop.BOp;
import com.bigdata.bop.BOpContext;
import com.bigdata.bop.HashMapAnnotations;
import com.bigdata.bop.IBindingSet;
import com.bigdata.bop.IPredicate;
import com.bigdata.bop.ISingleThreadedOp;
import com.bigdata.bop.NV;
import com.bigdata.bop.controller.INamedSolutionSetRef;
import com.bigdata.relation.accesspath.IAccessPath;
/**
* A hash join against an {@link IAccessPath} based on the Java collections
* classes. Source solutions are buffered on the Java collection on each
* evaluation pass. Once ALL source solutions have been buffered, the hash join
* will run a single pass over the {@link IAccessPath} for the target
* {@link IPredicate}. For some queries, this can be more efficient than probing
* as-bound instances of the target {@link IPredicate} using a nested indexed
* join, such as {@link PipelineJoin}. This can also be more efficient on a
* cluster where the key range scan of the target {@link IPredicate} will be
* performed using predominately sequential IO.
*
* The source solutions presented to a hash join MUST have bindings for the
* {@link HashJoinAnnotations#JOIN_VARS} in order to join (they can still
* succeed as optionals if the join variables are not bound).
*
* @see JVMHashJoinUtility
*
* @author Bryan Thompson
*/
public class JVMHashJoinOp extends HashJoinOp implements ISingleThreadedOp {
/**
*
*/
private static final long serialVersionUID = 1L;
public interface Annotations extends HashJoinOp.Annotations,
HashMapAnnotations {
}
/**
* @param op
*/
public JVMHashJoinOp(final JVMHashJoinOp op) {
super(op);
}
public JVMHashJoinOp(final BOp[] args, NV... annotations) {
this(args, NV.asMap(annotations));
}
/**
* @param args
* @param annotations
*/
public JVMHashJoinOp(final BOp[] args,
final Map annotations) {
super(args, annotations);
assertMaxParallelOne();
assertAtOnceJavaHeapOp();
}
@Override
protected IHashJoinUtility newState(final BOpContext context,
final INamedSolutionSetRef namedSetRef, final JoinTypeEnum joinType) {
return new JVMHashJoinUtility(this, joinType);
}
/**
* {@inheritDoc}
*
* The {@link JVMHashJoinOp} executes the hash join for each chunk of
* intermediate solutions (it is not an "at-once" operator).
*
* Note: Because this is an at-once operator, the solutions are all buffered
* on the query engine and this operator is invoked exactly once.
*
* Unlike the {@link HTreeHashJoinOp}, the concept of a LAST PASS evaluation
* does not enter in to the evaluation of this operator. However, by
* publishing the [state] on the query attribute we do gain visibility into
* the dynamics of the hash join while it is executing against the B+Tree
* access path.
*/
@Override
protected boolean runHashJoin(final BOpContext context,
final IHashJoinUtility state) {
return true;
}
}