| /* |
| * 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.pig.newplan.logical.optimizer; |
| |
| import java.util.List; |
| |
| import org.apache.pig.impl.logicalLayer.FrontendException; |
| import org.apache.pig.newplan.DependencyOrderWalker; |
| import org.apache.pig.newplan.DepthFirstWalker; |
| import org.apache.pig.newplan.OperatorPlan; |
| import org.apache.pig.newplan.logical.expression.LogicalExpressionPlan; |
| import org.apache.pig.newplan.logical.expression.LogicalExpressionVisitor; |
| import org.apache.pig.newplan.logical.expression.ProjectExpression; |
| import org.apache.pig.newplan.logical.relational.LOGenerate; |
| import org.apache.pig.newplan.logical.relational.LogicalRelationalOperator; |
| import org.apache.pig.newplan.logical.relational.LogicalSchema; |
| import org.apache.pig.newplan.optimizer.PlanTransformListener; |
| |
| /** |
| * A PlanTransformListener that will patch up references in projections. |
| * |
| */ |
| public class ProjectionPatcher implements PlanTransformListener { |
| |
| /** |
| * @link org.apache.pig.newplan.optimizer.PlanTransformListener#transformed(org.apache.pig.newplan.OperatorPlan, org.apache.pig.newplan.OperatorPlan) |
| */ |
| @Override |
| public void transformed(OperatorPlan fp, OperatorPlan tp) |
| throws FrontendException { |
| ProjectionFinder pf = new ProjectionFinder(tp); |
| pf.visit(); |
| } |
| |
| private static class ProjectionRewriter extends LogicalExpressionVisitor { |
| |
| ProjectionRewriter(OperatorPlan p, LogicalRelationalOperator cop) throws FrontendException { |
| super(p, new DepthFirstWalker(p)); |
| } |
| |
| @Override |
| public void visit(ProjectExpression p) throws FrontendException { |
| // if project is a project-star or range, ie it could not be expanded |
| // then its not possible to determine the matching input columns |
| // before runtime |
| if (p.isRangeOrStarProject()) { |
| return; |
| } |
| |
| // Get the uid for this projection. It must match the uid of the |
| // value it is projecting. |
| long myUid = p.getFieldSchema().uid; |
| |
| // Find the operator this projection references |
| LogicalRelationalOperator pred = p.findReferent(); |
| |
| if (p.getAttachedRelationalOp() instanceof LOGenerate && p.getPlan().getSuccessors(p)==null) { |
| // No need to adjust |
| return; |
| } |
| else { |
| // Get the schema for this operator and search it for the matching uid |
| int match = -1; |
| LogicalSchema schema = pred.getSchema(); |
| if (schema==null) |
| return; |
| List<LogicalSchema.LogicalFieldSchema> fields = schema.getFields(); |
| for (int i = 0; i < fields.size(); i++) { |
| if (fields.get(i).uid == myUid) { |
| match = i; |
| break; |
| } |
| } |
| if (match == -1) { |
| throw new FrontendException("Couldn't find matching uid " + match + " for project "+p, 2229); |
| } |
| p.setColNum(match); |
| } |
| } |
| } |
| |
| public static class ProjectionFinder extends AllExpressionVisitor { |
| |
| public ProjectionFinder(OperatorPlan plan) throws FrontendException { |
| super(plan, new DependencyOrderWalker(plan)); |
| } |
| |
| @Override |
| protected LogicalExpressionVisitor getVisitor(LogicalExpressionPlan expr) throws FrontendException { |
| return new ProjectionRewriter(expr, currentOp); |
| } |
| |
| } |
| } |