org.apache.hive.storage.jdbc.JdbcRecordReader.java Source code

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Here is the source code for org.apache.hive.storage.jdbc.JdbcRecordReader.java

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/*
 *
 * Licensed 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.hive.storage.jdbc;

import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.MapWritable;
import org.apache.hadoop.io.ObjectWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.RecordReader;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.apache.hive.storage.jdbc.dao.DatabaseAccessor;
import org.apache.hive.storage.jdbc.dao.DatabaseAccessorFactory;
import org.apache.hive.storage.jdbc.dao.JdbcRecordIterator;

import java.io.IOException;
import java.util.Map;
import java.util.Map.Entry;

public class JdbcRecordReader implements RecordReader<LongWritable, MapWritable> {

    private static final Logger LOGGER = LoggerFactory.getLogger(JdbcRecordReader.class);
    private DatabaseAccessor dbAccessor = null;
    private JdbcRecordIterator iterator = null;
    private JdbcInputSplit split = null;
    private JobConf conf = null;
    private int pos = 0;

    public JdbcRecordReader(JobConf conf, JdbcInputSplit split) {
        LOGGER.debug("Initializing JdbcRecordReader");
        this.split = split;
        this.conf = conf;
    }

    @Override
    public boolean next(LongWritable key, MapWritable value) throws IOException {
        try {
            LOGGER.debug("JdbcRecordReader.next called");
            if (dbAccessor == null) {
                dbAccessor = DatabaseAccessorFactory.getAccessor(conf);
                iterator = dbAccessor.getRecordIterator(conf, split.getLimit(), split.getOffset());
            }

            if (iterator.hasNext()) {
                LOGGER.debug("JdbcRecordReader has more records to read.");
                key.set(pos);
                pos++;
                Map<String, Object> record = iterator.next();
                if ((record != null) && (!record.isEmpty())) {
                    for (Entry<String, Object> entry : record.entrySet()) {
                        value.put(new Text(entry.getKey()), entry.getValue() == null ? NullWritable.get()
                                : new ObjectWritable(entry.getValue()));
                    }
                    return true;
                } else {
                    LOGGER.debug("JdbcRecordReader got null record.");
                    return false;
                }
            } else {
                LOGGER.debug("JdbcRecordReader has no more records to read.");
                return false;
            }
        } catch (Exception e) {
            LOGGER.error("An error occurred while reading the next record from DB.", e);
            return false;
        }
    }

    @Override
    public LongWritable createKey() {
        return new LongWritable();
    }

    @Override
    public MapWritable createValue() {
        return new MapWritable();
    }

    @Override
    public long getPos() throws IOException {
        return pos;
    }

    @Override
    public void close() throws IOException {
        if (iterator != null) {
            iterator.close();
        }
    }

    @Override
    public float getProgress() throws IOException {
        if (split == null) {
            return 0;
        } else {
            return split.getLength() > 0 ? pos / (float) split.getLength() : 1.0f;
        }
    }

    public void setDbAccessor(DatabaseAccessor dbAccessor) {
        this.dbAccessor = dbAccessor;
    }

    public void setIterator(JdbcRecordIterator iterator) {
        this.iterator = iterator;
    }

}