CODEWITHSUNDEEP
javahbase
ThisClark
ThisClark

Reputation: 14823

How to get timestamped versions of HBase cell

How do I return all timestamped versions of an HBase cell with the Get.setMaxVersions(10) method where 10 is an arbitrary number (could be something else like 20 or 5)? The following is a console main method that creates a table, inserts 10 random integers, and tries to retrieve all of them to print out.

public static void main(String[] args)
    throws ZooKeeperConnectionException, MasterNotRunningException, IOException, InterruptedException {

final String HBASE_ZOOKEEPER_QUORUM_IP = "localhost.localdomain"; //set ip in hosts file
final String HBASE_ZOOKEEPER_PROPERTY_CLIENTPORT = "2181";
final String HBASE_MASTER = HBASE_ZOOKEEPER_QUORUM_IP + ":60010";

//identify a data cell with these properties
String tablename = "characters";
String row = "johnsmith";
String family = "capital";
String qualifier = "A"; 

//config
Configuration config = HBaseConfiguration.create();
config.clear();
config.set("hbase.zookeeper.quorum", HBASE_ZOOKEEPER_QUORUM_IP);
config.set("hbase.zookeeper.property.clientPort", HBASE_ZOOKEEPER_PROPERTY_CLIENTPORT);
config.set("hbase.master", HBASE_MASTER);

//admin
HBaseAdmin hba = new HBaseAdmin(config);

//create a table
HTableDescriptor descriptor = new HTableDescriptor(tablename);
descriptor.addFamily(new HColumnDescriptor(family));
hba.createTable(descriptor);
hba.close();

//get the table
HTable htable = new HTable(config, tablename);

//insert 10 different timestamps into 1 record
for(int i = 0; i < 10; i++) {
    String value = Integer.toString(i);
    Put put = new Put(Bytes.toBytes(row));
    put.add(Bytes.toBytes(family), Bytes.toBytes(qualifier), System.currentTimeMillis(), Bytes.toBytes(value));
    htable.put(put);
    Thread.sleep(200); //make sure each timestamp is different
}

//get 10 timestamp versions of 1 record
final int MAX_VERSIONS = 10;
Get get = new Get(Bytes.toBytes(row));
get.setMaxVersions(MAX_VERSIONS);
Result result = htable.get(get);
byte[] value = result.getValue(Bytes.toBytes(family), Bytes.toBytes(qualifier));  // returns MAX_VERSIONS quantity of values
String output = Bytes.toString(value);

//show me what you got
System.out.println(output); //prints 9 instead of 0 through 9
}

The output is 9 (because the loop ended at i=9, and I don't see multiple versions in Hue's HBase Browser web UI. What can I do to fix the versions so it gives me 10 individual results for 0 - 9 instead of one result of only the number 9?

Upvotes: 1

Views: 4360

Answers (2)

ThisClark
ThisClark

Reputation: 14823

This is a deprecated approach which matches the version of HBase I am currently working on. 

List<KeyValue> kvpairs = result.getColumn(Bytes.toBytes(family), Bytes.toBytes(qualifier));
String line = "";
for(KeyValue kv : kvpairs) {
    line += Bytes.toString(kv.getValue()) + "\n";
}
System.out.println(line);

Then, going one step further, it is important to note the setMaxVersions method must be called at table creation to allow for more than a default three values to be inserted into a cell. Here's the updated table creation:

//create a table based on variables from question above
HTableDescriptor tableDescriptor = new HTableDescriptor(tablename);
HColumnDescriptor columnDescriptor = new HColumnDescriptor(columnFamily);
columnDescriptor.setMaxVersions(MAX_VERSIONS);
tableDescriptor.addFamily(columnDescriptor);
hba.createTable(tableDescriptor);
hba.close();

Upvotes: 0

Kapil Balagi
Kapil Balagi

Reputation: 1124

You should use getColumnCells on Result to get all versions (depending on MAX_VERSION_COUNT you have set in Get). getValue returns the latest value.

Sample Code:

    List<Cell> values = result.getColumnCells(Bytes.toBytes(family), Bytes.toBytes(qualifier));
    for ( Cell cell : values )
    {
        System.out.println( Bytes.toString( CellUtil.cloneValue( cell ) ) );
    }

Upvotes: 3

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