Function Description

HBase allows you to create a table using the createTable method of the org.apache.hadoop.hbase.client.Admin object. You need to specify a table name and a column family name. You can create a table by using either of the following methods, but the latter one is recommended.

• Quickly create a table. A newly created table contains only one region, which will be automatically split into multiple new regions as data increases.
• Create a table using pre-assigned regions. You can pre-assign multiple regions before creating a table. This mode accelerates data write at the beginning of massive data write.

The column name and column family name of a table consist of letters, digits, and underscores (_) but cannot contain any special characters.

Sample Code

The following code snippets are in the testCreateTable method in the HBaseSample class of the com.huawei.bigdata.hbase.examples packet.

For MRS 2.0.0 or later, use the following code to create a table:
public static void testCreateTable() {
    LOG.info("Entering testCreateTable.");
    // Set the column family name.
    byte [] fam = Bytes.toBytes("info");
    ColumnFamilyDescriptor familyDescriptor = ColumnFamilyDescriptorBuilder.newBuilder(fam)
        // Set data encoding methods. HBase provides DIFF,FAST_DIFF,PREFIX        
        // HBase 2.0 removed `PREFIX_TREE` Data Block Encoding from column families.
        .setDataBlockEncoding(DataBlockEncoding.FAST_DIFF)
        // Set compression methods, HBase provides two default compression        
        // methods:GZ and SNAPPY        
        // GZ has the highest compression rate,but low compression and        
        // decompression effeciency,fit for cold data        
        // SNAPPY has low compression rate, but high compression and        
        // decompression effeciency,fit for hot data.        
        // it is advised to use SANPPY
        .setCompressionType(Compression.Algorithm.SNAPPY)
        .build();
    TableDescriptor htd =
          TableDescriptorBuilder.newBuilder(tableName).setColumnFamily(familyDescriptor).build();

    Admin admin = null;
    try {
        // Instantiate an Admin object.
        admin = conn.getAdmin();
        if (!admin.tableExists(tableName)) {
            LOG.info("Creating table...");
            // create table
            admin.createTable(htd);
            LOG.info(admin.getClusterMetrics());
            LOG.info(admin.listNamespaceDescriptors());
            LOG.info("Table created successfully.");
        } else {
            LOG.warn("table already exists");
        }
    } catch (IOException e) {
        LOG.error("Create table failed.", e);
    } finally {
        if (admin != null) {
            try {
                // Close the Admin object.
                admin.close();
            } catch (IOException e) {
                LOG.error("Failed to close admin ", e);
            }
        }
    }
    LOG.info("Exiting testCreateTable.");
}

For versions earlier than MRS 2.0.0, use the following code to create a table:
public static void testCreateTable() {
    LOG.info("Entering testCreateTable.");
    // Specify the table descriptor.
    HTableDescriptor htd = new HTableDescriptor(tableName);

    // Set the column family name to info.
    HColumnDescriptor hcd = new HColumnDescriptor("info");

    // Set data encoding methods.HBase provides DIFF,FAST_DIFF,PREFIX
    // and PREFIX_TREE
    hcd.setDataBlockEncoding(DataBlockEncoding.FAST_DIFF);

    // Set compression methods,HBase provides two default compression
    // methods:GZ and SNAPPY
    // GZ has the highest compression rate,but low compression and
    // decompression effeciency,fit for cold data
    // SNAPPY has low compression rate, but high compression and
    // decompression effeciency,fit for hot data.
    // it is advised to use SANPPY
    hcd.setCompressionType(Compression.Algorithm.SNAPPY);

    htd.addFamily(hcd);

    Admin admin = null;
    try {
        // Instantiate an Admin object.
        admin = conn.getAdmin();
        if (!admin.tableExists(tableName)) {
            LOG.info("Creating table...");
            // create table
            admin.createTable(htd);
            LOG.info(admin.getClusterStatus());
            LOG.info(admin.listNamespaceDescriptors());
            LOG.info("Table created successfully.");
        } else {
            LOG.warn("table already exists");
        }
    } catch (IOException e) {
        LOG.error("Create table failed.", e);
    } finally {
        if (admin != null) {
            try {
                // Close the Admin object.
                admin.close();
            } catch (IOException e) {
                LOG.error("Failed to close admin ", e);
            }
        }
    }
    LOG.info("Exiting testCreateTable.");
}