| /* |
| * 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.vxquery.compiler.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.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.LogicalExpressionTag; |
| 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.expressions.AbstractFunctionCallExpression; |
| import org.apache.hyracks.algebricks.core.algebra.expressions.VariableReferenceExpression; |
| import org.apache.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator; |
| import org.apache.hyracks.algebricks.core.algebra.operators.logical.AbstractScanOperator; |
| import org.apache.hyracks.algebricks.core.algebra.operators.logical.AssignOperator; |
| import org.apache.hyracks.algebricks.core.algebra.operators.logical.UnnestOperator; |
| import org.apache.vxquery.functions.BuiltinOperators; |
| |
| /** |
| * The rule searches for an unnest operator (1) immediately following an unnest |
| * or data scan operator (2). If the variable is only used in unnest (1) then |
| * unnest (1) can be removed. |
| * |
| * <pre> |
| * Before |
| * |
| * plan__parent |
| * UNNEST( $v2 : iterate( $v1 ) ) |
| * UNNEST( $v1 : $v ) |
| * plan__child |
| * |
| * Where $v1 is not used in plan__parent. |
| * |
| * After |
| * |
| * plan__parent |
| * ASSIGN( $v2 : $v1 ) |
| * UNNEST( $v1 : $v ) |
| * plan__child |
| * </pre> |
| * |
| * @author prestonc |
| */ |
| public class RemoveUnusedUnnestIterateRule extends AbstractUsedVariablesProcessingRule { |
| |
| protected boolean processOperator(Mutable<ILogicalOperator> opRef, IOptimizationContext context) |
| throws AlgebricksException { |
| AbstractLogicalOperator op = (AbstractLogicalOperator) opRef.getValue(); |
| if (op.getOperatorTag() != LogicalOperatorTag.UNNEST) { |
| return false; |
| } |
| UnnestOperator unnest = (UnnestOperator) op; |
| |
| // Check to see if the expression is a function and iterate. |
| ILogicalExpression logicalExpressionUnnest1 = (ILogicalExpression) unnest.getExpressionRef().getValue(); |
| if (logicalExpressionUnnest1.getExpressionTag() != LogicalExpressionTag.FUNCTION_CALL) { |
| return false; |
| } |
| AbstractFunctionCallExpression functionCallUnnest1 = (AbstractFunctionCallExpression) logicalExpressionUnnest1; |
| if (!functionCallUnnest1.getFunctionIdentifier().equals(BuiltinOperators.ITERATE.getFunctionIdentifier())) { |
| return false; |
| } |
| |
| // Check to see if the expression is a variable. |
| Mutable<ILogicalExpression> logicalExpressionUnnestRef2 = functionCallUnnest1.getArguments().get(0); |
| ILogicalExpression logicalExpressionUnnest2 = (ILogicalExpression) logicalExpressionUnnestRef2.getValue(); |
| if (logicalExpressionUnnest2.getExpressionTag() != LogicalExpressionTag.VARIABLE) { |
| return false; |
| } |
| VariableReferenceExpression vre2 = (VariableReferenceExpression) logicalExpressionUnnest2; |
| LogicalVariable unnestInput = vre2.getVariableReference(); |
| |
| // Check if the input is an DATASCAN or UNNEST operator.. |
| Mutable<ILogicalOperator> opRef2 = unnest.getInputs().get(0); |
| AbstractLogicalOperator op2 = (AbstractLogicalOperator) opRef2.getValue(); |
| if (op2.getOperatorTag() == LogicalOperatorTag.UNNEST |
| || op2.getOperatorTag() == LogicalOperatorTag.DATASOURCESCAN) { |
| AbstractScanOperator aso = (AbstractScanOperator) op2; |
| if (aso.getVariables().size() == 1 && aso.getVariables().contains(unnestInput)) { |
| // Add in a noop. |
| AssignOperator assign = new AssignOperator(unnest.getVariable(), logicalExpressionUnnestRef2); |
| assign.getInputs().addAll(unnest.getInputs()); |
| opRef.setValue(assign); |
| return true; |
| } |
| } |
| return false; |
| } |
| } |