org.apache.hadoop.hive.ql.io.OneNullRowInputFormat Maven / Gradle / Ivy
/**
* 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.io;
import java.io.IOException;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.mapred.InputSplit;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.RecordReader;
import org.apache.hadoop.mapred.Reporter;
/**
* OneNullRowInputFormat outputs one null row. Used in implementation of
* metadata only queries.
*
*/
public class OneNullRowInputFormat extends NullRowsInputFormat {
@Override
public RecordReader getRecordReader(InputSplit arg0,
JobConf arg1, Reporter arg2) throws IOException {
return new OneNullRowRecordReader();
}
public static class OneNullRowRecordReader extends NullRowsRecordReader {
private boolean processed;
@Override
public long getPos() throws IOException {
return processed ? 1 : 0;
}
@Override
public float getProgress() throws IOException {
return processed ? 1.0f : 0f;
}
@Override
public boolean next(NullWritable key, NullWritable value) throws IOException {
if (processed) {
return false;
}
processed = true;
return true;
}
}
}