HBASE & Java: Search for Data

This tutorial will give you a quick overview of how to search for data using HBASE. If you have not done so yet. Follow the following two tutorials on HBASE: Connecting and HBASE: Create a Table.

Search for Data:

Basically we have to scan the table for data. So we must first setup a scan object then search for the data.

import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.client.ResultScanner;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.Cell;
import org.apache.hadoop.hbase.client.Table;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.util.Bytes;
 
//Lets setup our scan object.
final Scan scan = new Scan();
//Search a particular column
scan.addColumn(Bytes.toBytes("columnFamily"), Bytes.toBytes("columnName"));
//Check the row key prefix
scan.setRowPrefixFilter(Bytes.toBytes("rowkey"));
 
final TableName table = TableName.valueOf(yourTableName);
 
//Get the table you want to work with. using the connection from the tutorial above.
final Table table = conn.getTable(table);
//Create our scanner based on the scan object above.
final ResultScanner scanner = table.getScanner(scan);
 
//Now we will loop through our results
for (Result result = scanner.next(); result != null; result = scanner.next()) {
      //Lets get our row key
      final String rowIdentifier = Bytes.toString(result.getRow());
 
      //Now based on each record found we will loop through the available cells for that record.
      for (final Cell cell : result.listCells()) {
        //now we can do whatever we need to with the data.
        log.info("column {} value {}", Bytes.toString(cell.getQualifierArray(), cell.getQualifierOffset(), cell.getQualifierLength()), Bytes.toString(cell.getValueArray(), cell.getValueOffset(), cell.getValueLength()));
      }
}