HBase用戶端API-Batch操作

上一篇部落格說了使用 HBase 的用戶端 API 來操作操作 HBase 表中記錄，今天我們看看怎樣通過 API 來大量操作表中的資料。

安裝上一篇部落格中的方法在 HBase 中如果更新（添加/修改/刪除）記錄，是按行一條一條更新的，這種方法在處理大量更新操作時，效能比較差，還好在 HBase 中提供了以 Batch 方式來批次更新資料表的方法。下面就看看怎樣通過 Table.batch() 方法來批次更新

要使用 Table 的 batch 模式批次更新，我們需要建立一個Put操作的集合，同時提供和一個和Put操作集合長度相等的Object對象數組，用來存放操作結果。然後再調用 “table.batch(actions, results);” 即可，看下面程式碼片段。

    private void batch() throws IOException {        // 建立表        ...        Table table = connection.getTable(TableName.valueOf(TABLE_NAME));        List<Row> actions = new ArrayList<Row>();        for (int i = 0; i < 10000; i++) {            Put put = new Put(Bytes.toBytes("row_" + i));            put.addColumn(Bytes.toBytes(COLUMN_FAMILY_BASE), Bytes.toBytes(COLUMN_USERNAME), Bytes.toBytes("user_" + i));            put.addColumn(Bytes.toBytes(COLUMN_FAMILY_BASE), Bytes.toBytes(COLUMN_PASSWORD), Bytes.toBytes("password_" + i));            put.addColumn(Bytes.toBytes(COLUMN_FAMILY_ADDRESS), Bytes.toBytes(COLUMN_HOME), Bytes.toBytes("home_" + i));            put.addColumn(Bytes.toBytes(COLUMN_FAMILY_ADDRESS), Bytes.toBytes(COLUMN_OFFICE), Bytes.toBytes("office_" + i));            actions.add(put);        }        Object[] results = new Object[actions.size()];        try {            table.batch(actions, results);        } catch (InterruptedException e) {            e.printStackTrace();        }        Scan scan = new Scan();        ResultScanner resultScanner = table.getScanner(scan);        Iterator<Result> it = resultScanner.iterator();        while (it.hasNext()) {            Result result = it.next();            printRow(result);        }        table.close();        // 刪除表        ...    }

完整例子代碼如下

package my.hbasestudy;import org.apache.hadoop.conf.Configuration;import org.apache.hadoop.hbase.HBaseConfiguration;import org.apache.hadoop.hbase.TableName;import org.apache.hadoop.hbase.client.*;import org.apache.hadoop.hbase.util.Bytes;import java.io.IOException;import java.util.ArrayList;import java.util.Iterator;import java.util.List;public class TestBatch {    private static final String TABLE_NAME = "user";    private static final String COLUMN_FAMILY_BASE = "base";    private static final String COLUMN_FAMILY_ADDRESS = "address";    private static final String COLUMN_USERNAME = "username";    private static final String COLUMN_PASSWORD = "password";    private static final String COLUMN_HOME = "home";    private static final String COLUMN_OFFICE = "office";    private Connection connection;    public static void main(String[] args) throws Exception {        Configuration config = HBaseConfiguration.create();        Connection connection = ConnectionFactory.createConnection(config);        long t1 = System.currentTimeMillis();        TestBatch t = new TestBatch(connection);        t.batch();        long t2 = System.currentTimeMillis();        System.out.println("Time: " + (t2 - t1));        connection.close();    }    public TestBatch(Connection connection) {        this.connection = connection;    }    private void batch() throws IOException {        createTable();        Table table = connection.getTable(TableName.valueOf(TABLE_NAME));        List<Row> actions = new ArrayList<Row>();        for (int i = 0; i < 10000; i++) {            Put put = new Put(Bytes.toBytes("row_" + i));            put.addColumn(Bytes.toBytes(COLUMN_FAMILY_BASE), Bytes.toBytes(COLUMN_USERNAME), Bytes.toBytes("user_" + i));            put.addColumn(Bytes.toBytes(COLUMN_FAMILY_BASE), Bytes.toBytes(COLUMN_PASSWORD), Bytes.toBytes("password_" + i));            put.addColumn(Bytes.toBytes(COLUMN_FAMILY_ADDRESS), Bytes.toBytes(COLUMN_HOME), Bytes.toBytes("home_" + i));            put.addColumn(Bytes.toBytes(COLUMN_FAMILY_ADDRESS), Bytes.toBytes(COLUMN_OFFICE), Bytes.toBytes("office_" + i));            actions.add(put);        }        Object[] results = new Object[actions.size()];        try {            table.batch(actions, results);        } catch (InterruptedException e) {            e.printStackTrace();        }        Scan scan = new Scan();        ResultScanner resultScanner = table.getScanner(scan);        Iterator<Result> it = resultScanner.iterator();        while (it.hasNext()) {            Result result = it.next();            printRow(result);        }        table.close();        deleteTable();    }    private void createTable() throws IOException {        Admin admin = connection.getAdmin();        try {            TableDescriptor tableDesc = TableDescriptorBuilder.newBuilder(TableName.valueOf(TABLE_NAME))                    .addColumnFamily(ColumnFamilyDescriptorBuilder.newBuilder(Bytes.toBytes(COLUMN_FAMILY_BASE)).build())                    .addColumnFamily(ColumnFamilyDescriptorBuilder.newBuilder(Bytes.toBytes(COLUMN_FAMILY_ADDRESS)).build())                    .build();            admin.createTable(tableDesc);        } finally {            admin.close();        }    }    private void deleteTable() throws IOException {        Admin admin = connection.getAdmin();        try {            admin.disableTable(TableName.valueOf(TABLE_NAME));            admin.deleteTable(TableName.valueOf(TABLE_NAME));        } finally {            admin.close();        }    }    private void printRow(Result result) {        if (Bytes.toString(result.getRow()) != null) {            StringBuilder sb = new StringBuilder();            sb.append(Bytes.toString(result.getRow()));            sb.append("[");            sb.append("base:username=" + Bytes.toString(result.getValue(Bytes.toBytes("base"), Bytes.toBytes("username"))));            sb.append(", base:password=" + Bytes.toString(result.getValue(Bytes.toBytes("base"), Bytes.toBytes("password"))));            sb.append(", address:home=" + Bytes.toString(result.getValue(Bytes.toBytes("address"), Bytes.toBytes("home"))));            sb.append(", address:office=" + Bytes.toString(result.getValue(Bytes.toBytes("address"), Bytes.toBytes("office"))));            sb.append("]");            System.out.println(sb.toString());        }    }}