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* 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.relational;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import org.apache.pig.PigException;
import org.apache.pig.impl.logicalLayer.FrontendException;
import org.apache.pig.impl.util.Pair;
import org.apache.pig.newplan.Operator;
import org.apache.pig.newplan.OperatorPlan;
import org.apache.pig.newplan.PlanVisitor;
import org.apache.pig.newplan.logical.expression.LogicalExpression;
import org.apache.pig.newplan.logical.relational.LogicalSchema.LogicalFieldSchema;
public class LOUnion extends LogicalRelationalOperator {
private boolean onSchema;
// uid mapping from output uid to input uid
private List<Pair<Long, Long>> uidMapping = new ArrayList<Pair<Long, Long>>();
public LOUnion(OperatorPlan plan) {
super("LOUnion", plan);
}
public LOUnion(OperatorPlan plan, boolean onSchema) {
this( plan );
this.onSchema = onSchema;
}
public boolean isOnSchema() {
return onSchema;
}
@Override
public LogicalSchema getSchema() throws FrontendException {
if (schema != null) {
return schema;
}
List<Operator> inputs = plan.getPredecessors(this);
// If any predecessor's schema is null, then the schema for union is null
for (Operator input : inputs) {
LogicalRelationalOperator op = (LogicalRelationalOperator)input;
if( op.getSchema() == null ) {
if( isOnSchema() ) {
String msg = "Schema of relation " + op.getAlias()
+ " is null."
+ " UNION ONSCHEMA cannot be used with relations that"
+ " have null schema.";
throw new FrontendException(this, msg, 1116, PigException.INPUT);
} else {
return null;
}
}
}
LogicalSchema mergedSchema = null;
LogicalSchema s0 = ((LogicalRelationalOperator)inputs.get(0)).getSchema();
if ( inputs.size() == 1 )
return schema = s0;
if( isOnSchema() ) {
mergedSchema = createMergedSchemaOnAlias( inputs );
} else {
LogicalSchema s1 = ((LogicalRelationalOperator)inputs.get(1)).getSchema();
mergedSchema = LogicalSchema.merge(s0, s1, LogicalSchema.MergeMode.Union);
if (mergedSchema==null)
return null;
// Merge schema
for (int i=2;i<inputs.size();i++) {
LogicalSchema otherSchema = ((LogicalRelationalOperator)inputs.get(i)).getSchema();
if (mergedSchema==null || otherSchema==null)
return null;
mergedSchema = LogicalSchema.merge(mergedSchema, otherSchema, LogicalSchema.MergeMode.Union);
if (mergedSchema == null)
return null;
}
}
// Bring back cached uid if any; otherwise, cache uid generated
for (int i=0;i<s0.size();i++)
{
LogicalSchema.LogicalFieldSchema outputFieldSchema;
if (onSchema) {
outputFieldSchema = mergedSchema.getFieldSubNameMatch(s0.getField(i).alias);
} else {
outputFieldSchema = mergedSchema.getField(i);
}
long uid = -1;
for (Pair<Long, Long> pair : uidMapping) {
if (pair.second==s0.getField(i).uid) {
uid = pair.first;
break;
}
}
if (uid==-1) {
uid = LogicalExpression.getNextUid();
for (Operator input : inputs) {
long inputUid;
LogicalFieldSchema matchedInputFieldSchema;
if (onSchema) {
matchedInputFieldSchema = ((LogicalRelationalOperator)input).getSchema().getFieldSubNameMatch(s0.getField(i).alias);
if (matchedInputFieldSchema!=null) {
inputUid = matchedInputFieldSchema.uid;
uidMapping.add(new Pair<Long, Long>(uid, inputUid));
}
}
else {
matchedInputFieldSchema = mergedSchema.getField(i);
inputUid = ((LogicalRelationalOperator)input).getSchema().getField(i).uid;
uidMapping.add(new Pair<Long, Long>(uid, inputUid));
}
}
}
outputFieldSchema.uid = uid;
}
return schema = mergedSchema;
}
/**
* create schema for union-onschema
*/
private LogicalSchema createMergedSchemaOnAlias(List<Operator> ops)
throws FrontendException {
ArrayList<LogicalSchema> schemas = new ArrayList<LogicalSchema>();
for( Operator op : ops ){
LogicalRelationalOperator lop = (LogicalRelationalOperator)op;
LogicalSchema sch = lop.getSchema();
for( LogicalFieldSchema fs : sch.getFields() ) {
if(fs.alias == null){
String msg = "Schema of relation " + lop.getAlias()
+ " has a null fieldschema for column(s). Schema :" + sch.toString(false);
throw new FrontendException( this, msg, 1116, PigException.INPUT );
}
}
schemas.add( sch );
}
//create the merged schema
LogicalSchema mergedSchema = null;
try {
mergedSchema = LogicalSchema.mergeSchemasByAlias( schemas );
} catch(FrontendException e) {
String msg = "Error merging schemas for union operator : "
+ e.getMessage();
throw new FrontendException(this, msg, 1116, PigException.INPUT, e);
}
return mergedSchema;
}
@Override
public void accept(PlanVisitor v) throws FrontendException {
if (!(v instanceof LogicalRelationalNodesVisitor)) {
throw new FrontendException("Expected LogicalPlanVisitor", 2223);
}
((LogicalRelationalNodesVisitor)v).visit(this);
}
@Override
public boolean isEqual(Operator other) throws FrontendException {
if (other != null && other instanceof LOUnion) {
return checkEquality((LOUnion)other);
} else {
return false;
}
}
// Get input uids mapping to the output uid
public Set<Long> getInputUids(long uid) {
Set<Long> result = new HashSet<Long>();
for (Pair<Long, Long> pair : uidMapping) {
if (pair.first==uid)
result.add(pair.second);
}
return result;
}
@Override
public void resetUid() {
uidMapping = new ArrayList<Pair<Long, Long>>();
}
public List<Operator> getInputs() {
return plan.getPredecessors(this);
}
public List<Operator> getInputs(LogicalPlan plan) {
return plan.getPredecessors(this);
}
public void setUnionOnSchema(boolean flag) {
onSchema = flag;
}
}