The Get operation can fetch certain records from an HBase table. It is similar to the select [fields] where RowKey=<Row Key value here> statement in relational databases, where we fetch a row from the table.

The following is the representation of Get:

public Result get(Get get)throws IOException

In the preceding code, the Get operation can be provided as a single get object out of a list of get objects as get(List<Get> gets). It is specified by Get in the HTableInterface interface given by HBase. The Get operation receives the get parameter, which objects the data that is to be fetched from the table. It returns data of the particular row, which is specified in the get object as an HBase Result object, and this throws IOException when not able to read.

We will see how to use these methods in Java in Chapter 8, Coding HBase in Java, and Chapter 9, Advance Coding in Java for HBase.

On HBase shell, it can be used as follows:

get 'table name', 'row key',<filters>

The Put operation adds a new row of data to a table or updates/overrides a specific row of data. It is executed through HTable.put() or HTable.batch(), which is a batch write operation.

This takes put as parameter. We can see its use as follows:

public void put(Put put) throws InterruptedIOException,RetriesExhaustedWithDetailsException

This also takes a single put object or a list of put objects to write a set of values in a table.

The Scan operation can be used to read multiple rows of data in contrast to Get where we need to specify a set of rows to read data. However, in the case of a scan, we can iterate through a range of rows or all the rows in a table.

It can be used as follows (Java code):

HBaseConfiguration conf = HBaseConfiguration.create();
HTable table1 = new HTable(conf, "hbaseTable");
Scan scanObj = new Scan();
ResultScannerrs = htable.getScanner(scanObj);

Also, we can iterate through a result-set object and get each row in the result object.

The Delete operation removes a row or a set of rows from a table. It is executed through HTable.delete(). Once a row is set to be deleted, it is marked as tombstone, and once compaction takes place, the row is finally deleted or removed from a table.

public void delete (Delete delete) throws IOException

delete is specified as an interface of HTableInterface, takes the delete object or delete list as a parameter, and throws IOException if any intermediate exception occurs.

The Delete happens for the following: