org.apache.hadoop.vertica.VerticaInputSplit.java Source code

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Here is the source code for org.apache.hadoop.vertica.VerticaInputSplit.java

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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.hadoop.vertica;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.mapreduce.InputSplit;

/**
 * Input split class for reading data from Vertica
 * 
 */
public class VerticaInputSplit extends InputSplit implements Writable {
    private static final Log LOG = LogFactory.getLog(VerticaInputSplit.class);

    PreparedStatement stmt = null;
    Connection connection = null;
    VerticaConfiguration vtconfig = null;
    String inputQuery = null;
    List<Object> segmentParams = null;
    long start = 0;
    long end = 0;

    /** (@inheritDoc) */
    public VerticaInputSplit() {
        LOG.trace("Input split default constructor");
    }

    /**
     * Set the input query and a list of parameters to substitute when evaluating
     * the query
     * 
     * @param inputQuery
     *          SQL query to run
     * @param segmentParams
     *          list of parameters to substitute into the query
     * @param start
     *          the logical starting record number
     * @param end
     *          the logical ending record number
     */
    public VerticaInputSplit(String inputQuery, List<Object> segmentParams, long start, long end) {
        LOG.trace("Input split constructor with query and params");
        this.inputQuery = inputQuery;
        this.segmentParams = segmentParams;
        this.start = start;
        this.end = end;
    }

    /** (@inheritDoc) */
    public void configure(Configuration conf) throws Exception {
        LOG.trace("Input split configured");
        vtconfig = new VerticaConfiguration(conf);
        connection = vtconfig.getConnection(false);
        connection.setAutoCommit(true);
        connection.setTransactionIsolation(Connection.TRANSACTION_READ_COMMITTED);
    }

    /**
     * Return the parameters used for input query
     * 
     */
    public List<Object> getSegmentParams() {
        return segmentParams;
    }

    /**
     * Run the query that, when executed returns input for the mapper
     * 
     * @throws Exception
     */
    public ResultSet executeQuery() throws Exception {
        LOG.trace("Input split execute query");
        long length = getLength();

        if (length != 0)
            inputQuery = "SELECT * FROM ( " + inputQuery + " ) limited LIMIT ? OFFSET ?";

        if (connection == null)
            throw new Exception("Cannot execute query with no connection");
        stmt = connection.prepareStatement(inputQuery);

        int i = 1;
        if (segmentParams != null)
            for (Object param : segmentParams)
                stmt.setObject(i++, param);

        if (length != 0) {
            stmt.setLong(i++, length);
            stmt.setLong(i++, start);
        }

        ResultSet rs = stmt.executeQuery();
        return rs;
    }

    /** (@inheritDoc) */
    public void close() throws SQLException {
        stmt.close();
    }

    /**
     * @return The index of the first row to select
     */
    public long getStart() {
        return start;
    }

    /**
     * @return The index of the last row to select
     */
    public long getEnd() {
        return end;
    }

    /**
     * @return The total row count in this split
     */
    public long getLength() throws IOException {
        // TODO: figureout how to return length when there is no start and end
        return end - start;
    }

    /** {@inheritDoc} */
    public String[] getLocations() throws IOException {
        return new String[] {};
    }

    /** (@inheritDoc) */
    public Configuration getConfiguration() {
        return vtconfig.getConfiguration();
    }

    /** {@inheritDoc} */
    public void readFields(DataInput in) throws IOException {
        inputQuery = Text.readString(in);
        long paramCount = in.readLong();
        if (paramCount > 0) {
            VerticaRecord record = new VerticaRecord();
            record.readFields(in);
            segmentParams = record.getValues();
        }
        start = in.readLong();
        end = in.readLong();
    }

    /** {@inheritDoc} */
    public void write(DataOutput out) throws IOException {
        Text.writeString(out, inputQuery);
        if (segmentParams != null && segmentParams.size() > 0) {
            out.writeLong(segmentParams.size());
            VerticaRecord record = new VerticaRecord(segmentParams, true);
            record.write(out);
        } else
            out.writeLong(0);
        out.writeLong(start);
        out.writeLong(end);
    }
}