BatchGetUDF.java

package brickhouse.hbase;
/**
 * Copyright 2012 Klout, Inc
 *
 * 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.
 *
 **/

import org.apache.hadoop.hbase.client.Get;
import org.apache.hadoop.hbase.client.HTable;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hive.ql.exec.Description;
import org.apache.hadoop.hive.ql.exec.UDF;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;

/**
 * Simple UDF for doing batch GET's from an HBase table ..
 * Not intended for doing massive reads from HBase,
 * but only when relatively few rows are being read.
 */
@Description(name = "hbase_batch_get",
        value = "_FUNC_(table,key,family) - Do a single HBase Get on a table "
)
public class BatchGetUDF extends UDF {

    public List<String> evaluate(Map<String, String> config, List<String> keys) {
        try {
            HTableFactory.checkConfig(config);
            HTable table = HTableFactory.getHTable(config);

            List<Get> getArr = new ArrayList<Get>();
            for (int i = 0; i < keys.size(); ++i) {
                String key = keys.get(i);
                Get theGet = new Get(key.getBytes());
                getArr.add(theGet);
            }
            Result[] results = table.get(getArr);

            ArrayList<String> resultList = new ArrayList<String>();
            for (int i = 0; i < results.length; ++i) {
                Result res = results[i];

                byte[] valBytes = res.getValue(config.get(HTableFactory.FAMILY_TAG).getBytes(), config.get(HTableFactory.QUALIFIER_TAG).getBytes());
                if (valBytes != null) {
                    resultList.add(new String(valBytes));
                } else {
                    resultList.add(null);
                }
            }

            return resultList;
        } catch (Exception exc) {
            ///LOG.error(" Error while trying HBase PUT ",exc);
            throw new RuntimeException(exc);
        }


    }

}