| /* |
| * Copyright 2009-2010 by The Regents of the University of California |
| * 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 from |
| * |
| * 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 edu.uci.ics.hyracks.algebricks.rewriter.rules; |
| |
| import java.util.ArrayList; |
| import java.util.HashSet; |
| import java.util.List; |
| import java.util.Set; |
| |
| import org.apache.commons.lang3.mutable.Mutable; |
| import org.apache.commons.lang3.mutable.MutableObject; |
| |
| import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException; |
| import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression; |
| import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator; |
| import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext; |
| import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag; |
| import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable; |
| import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.ConstantExpression; |
| import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator; |
| import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractScanOperator; |
| import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.EmptyTupleSourceOperator; |
| import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.InnerJoinOperator; |
| import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.visitors.VariableUtilities; |
| import edu.uci.ics.hyracks.algebricks.core.rewriter.base.IAlgebraicRewriteRule; |
| |
| public class SimpleUnnestToProductRule implements IAlgebraicRewriteRule { |
| |
| @Override |
| public boolean rewritePre(Mutable<ILogicalOperator> opRef, IOptimizationContext context) { |
| return false; |
| } |
| |
| @Override |
| public boolean rewritePost(Mutable<ILogicalOperator> opRef, IOptimizationContext context) |
| throws AlgebricksException { |
| AbstractLogicalOperator op = (AbstractLogicalOperator) opRef.getValue(); |
| if (op.getOperatorTag() != LogicalOperatorTag.DATASOURCESCAN |
| && op.getOperatorTag() != LogicalOperatorTag.UNNEST) { |
| return false; |
| } |
| |
| Mutable<ILogicalOperator> opRef2 = op.getInputs().get(0); |
| AbstractLogicalOperator op2 = (AbstractLogicalOperator) opRef2.getValue(); |
| |
| if (!(op2 instanceof AbstractScanOperator) && !descOrSelfIsSourceScan(op2)) { |
| return false; |
| } |
| // Make sure that op does not use any variables produced by op2. |
| if (!opsAreIndependent(op, op2)) { |
| return false; |
| } |
| |
| InnerJoinOperator product = new InnerJoinOperator( |
| new MutableObject<ILogicalExpression>(ConstantExpression.TRUE)); |
| |
| EmptyTupleSourceOperator ets = new EmptyTupleSourceOperator(); |
| context.computeAndSetTypeEnvironmentForOperator(ets); |
| Mutable<ILogicalOperator> emptySrc = new MutableObject<ILogicalOperator>(ets); |
| List<Mutable<ILogicalOperator>> opInpList = op.getInputs(); |
| opInpList.clear(); |
| opInpList.add(emptySrc); |
| product.getInputs().add(opRef2); // outer branch |
| product.getInputs().add(new MutableObject<ILogicalOperator>(op)); |
| opRef.setValue(product); // plug the product in the plan |
| context.computeAndSetTypeEnvironmentForOperator(product); |
| return true; |
| } |
| |
| private boolean descOrSelfIsSourceScan(AbstractLogicalOperator op2) { |
| // Disregard data source scans in a subplan. |
| if (op2.getOperatorTag() == LogicalOperatorTag.SUBPLAN) { |
| return false; |
| } |
| if (op2.getOperatorTag() == LogicalOperatorTag.DATASOURCESCAN |
| && op2.getOperatorTag() != LogicalOperatorTag.UNNEST) { |
| return true; |
| } |
| for (Mutable<ILogicalOperator> cRef : op2.getInputs()) { |
| AbstractLogicalOperator alo = (AbstractLogicalOperator) cRef.getValue(); |
| if (descOrSelfIsSourceScan(alo)) { |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| private boolean opsAreIndependent(ILogicalOperator unnestOp, ILogicalOperator outer) throws AlgebricksException { |
| List<LogicalVariable> opUsedVars = new ArrayList<LogicalVariable>(); |
| VariableUtilities.getUsedVariables(unnestOp, opUsedVars); |
| Set<LogicalVariable> op2LiveVars = new HashSet<LogicalVariable>(); |
| VariableUtilities.getLiveVariables(outer, op2LiveVars); |
| for (LogicalVariable usedVar : opUsedVars) { |
| if (op2LiveVars.contains(usedVar)) { |
| return false; |
| } |
| } |
| return true; |
| } |
| |
| } |