| /* |
| * 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 org.apache.commons.lang3.mutable.Mutable; |
| import org.apache.hyracks.algebricks.common.exceptions.AlgebricksException; |
| 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.expressions.ConstantExpression; |
| import org.apache.hyracks.algebricks.core.algebra.operators.logical.AbstractBinaryJoinOperator; |
| import org.apache.hyracks.algebricks.core.rewriter.base.IAlgebraicRewriteRule; |
| |
| /** |
| * Removes Cartesian product operators that have one input branch is EmptyTupleSource. |
| */ |
| public class RemoveCartesianProductWithEmptyBranchRule implements IAlgebraicRewriteRule { |
| |
| @Override |
| public boolean rewritePost(Mutable<ILogicalOperator> opRef, IOptimizationContext context) |
| throws AlgebricksException { |
| ILogicalOperator op = opRef.getValue(); |
| if (op.getOperatorTag() != LogicalOperatorTag.INNERJOIN |
| && op.getOperatorTag() != LogicalOperatorTag.LEFTOUTERJOIN) { |
| return false; |
| } |
| AbstractBinaryJoinOperator joinOperator = (AbstractBinaryJoinOperator) op; |
| ILogicalOperator left = joinOperator.getInputs().get(0).getValue(); |
| ILogicalOperator right = joinOperator.getInputs().get(1).getValue(); |
| |
| if (!joinOperator.getCondition().getValue().equals(ConstantExpression.TRUE)) { |
| return false; |
| } |
| if (emptyBranch(left)) { |
| opRef.setValue(right); |
| return true; |
| } |
| if (emptyBranch(right)) { |
| opRef.setValue(left); |
| return true; |
| } |
| return false; |
| } |
| |
| private boolean emptyBranch(ILogicalOperator op) { |
| return op.getOperatorTag() == LogicalOperatorTag.EMPTYTUPLESOURCE; |
| } |
| } |