/**
* 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.hadoop.hive.ql.exec;
import java.io.Serializable;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hive.ql.CompilationOpContext;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.ql.plan.LimitDesc;
import org.apache.hadoop.hive.ql.plan.api.OperatorType;
/**
* Limit operator implementation Limits the number of rows to be passed on.
**/
public class LimitOperator extends Operator<LimitDesc> implements Serializable {
private static final long serialVersionUID = 1L;
protected transient int limit;
protected transient int offset;
protected transient int leastRow;
protected transient int currCount;
protected transient boolean isMap;
/** Kryo ctor. */
protected LimitOperator() {
super();
}
public LimitOperator(CompilationOpContext ctx) {
super(ctx);
}
@Override
protected void initializeOp(Configuration hconf) throws HiveException {
super.initializeOp(hconf);
limit = conf.getLimit();
leastRow = conf.getLeastRows();
offset = (conf.getOffset() == null) ? 0 : conf.getOffset();
currCount = 0;
isMap = hconf.getBoolean("mapred.task.is.map", true);
}
@Override
public void process(Object row, int tag) throws HiveException {
if (offset <= currCount && currCount < (offset + limit)) {
forward(row, inputObjInspectors[tag]);
currCount++;
} else if (offset > currCount) {
currCount++;
} else {
setDone(true);
}
}
@Override
public String getName() {
return LimitOperator.getOperatorName();
}
static public String getOperatorName() {
return "LIM";
}
@Override
public OperatorType getType() {
return OperatorType.LIMIT;
}
@Override
public void closeOp(boolean abort) throws HiveException {
if (!isMap && currCount < leastRow) {
throw new HiveException("No sufficient row found");
}
super.closeOp(abort);
}
}