| /* |
| * 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.hyracks.algebricks.rewriter.rules; |
| |
| import java.util.HashSet; |
| import java.util.List; |
| import java.util.Set; |
| |
| import org.apache.commons.lang3.mutable.Mutable; |
| import org.apache.hyracks.algebricks.common.exceptions.AlgebricksException; |
| import org.apache.hyracks.algebricks.common.utils.Pair; |
| import org.apache.hyracks.algebricks.core.algebra.base.ILogicalExpression; |
| import org.apache.hyracks.algebricks.core.algebra.base.ILogicalOperator; |
| import org.apache.hyracks.algebricks.core.algebra.base.IOptimizationContext; |
| import org.apache.hyracks.algebricks.core.algebra.base.LogicalOperatorTag; |
| import org.apache.hyracks.algebricks.core.algebra.base.LogicalVariable; |
| import org.apache.hyracks.algebricks.core.algebra.operators.logical.OrderOperator; |
| import org.apache.hyracks.algebricks.core.algebra.operators.logical.OrderOperator.IOrder; |
| import org.apache.hyracks.algebricks.core.algebra.operators.logical.visitors.VariableUtilities; |
| import org.apache.hyracks.algebricks.core.rewriter.base.IAlgebraicRewriteRule; |
| |
| /** |
| * This rule pushes down the sort operator |
| * as much as possible to where the sort keys are available. |
| * The rule pushes the sort operator down one-step-at-a-time. |
| */ |
| public class PushSortDownRule implements IAlgebraicRewriteRule { |
| |
| @Override |
| public boolean rewritePre(Mutable<ILogicalOperator> opRef, IOptimizationContext context) |
| throws AlgebricksException { |
| ILogicalOperator operator = opRef.getValue(); |
| if (operator.getOperatorTag() != LogicalOperatorTag.ORDER) { |
| return false; |
| } |
| |
| // Gets used variables in the sort operator. |
| OrderOperator orderOperator = (OrderOperator) operator; |
| List<Pair<IOrder, Mutable<ILogicalExpression>>> orderKeys = orderOperator.getOrderExpressions(); |
| Set<LogicalVariable> orderUsedVars = new HashSet<LogicalVariable>(); |
| for (Pair<IOrder, Mutable<ILogicalExpression>> orderKey : orderKeys) { |
| orderKey.second.getValue().getUsedVariables(orderUsedVars); |
| } |
| Mutable<ILogicalOperator> inputOpRef = orderOperator.getInputs().get(0); |
| ILogicalOperator inputOperator = inputOpRef.getValue(); |
| |
| // Only pushes sort through assign: |
| // 1. Blocking operators like sort/group/join cannot be pushed through. |
| // 2. Data reducing operators like select/project should not be pushed through. |
| // 3. Order-destroying operator like unnest/unnest-map cannot be pushed through. |
| if (inputOperator.getOperatorTag() != LogicalOperatorTag.ASSIGN) { |
| return false; |
| } |
| Set<LogicalVariable> inputProducedVars = new HashSet<LogicalVariable>(); |
| VariableUtilities.getProducedVariables(inputOperator, inputProducedVars); |
| |
| // Intersects used variables in the sort and variables produced by inputOperator. |
| orderUsedVars.retainAll(inputProducedVars); |
| if (!orderUsedVars.isEmpty()) { |
| // If the sort uses any variable that is produced by this operator. |
| return false; |
| } |
| |
| // Switches sort and its input operator. |
| opRef.setValue(inputOperator); |
| inputOpRef.setValue(inputOperator.getInputs().get(0).getValue()); |
| inputOperator.getInputs().get(0).setValue(orderOperator); |
| |
| // Re-computes the type environments. |
| context.computeAndSetTypeEnvironmentForOperator(orderOperator); |
| context.computeAndSetTypeEnvironmentForOperator(inputOperator); |
| return true; |
| } |
| |
| @Override |
| public boolean rewritePost(Mutable<ILogicalOperator> opRef, IOptimizationContext context) |
| throws AlgebricksException { |
| return false; |
| } |
| |
| } |