The append() methods allow you to add information to an existing key/value pair in the database. You can use this to add information to a string or other data after the existing data.

The append() methods append raw serialized data on to the end of the existing data in the key. If you have previously stored a serialized object into Couchbase and then use append, the content of the serialized object will not be extended. For example, adding an Array of integers into the database, and then using append() to add another integer will result in the key referring to a serialized version of the array, immediately followed by a serialized version of the integer. It will not contain an updated array with the new integer appended to it. De-serialization of objects that have had data appended may result in data corruption.

The append() appends information to the end of an existing key/value pair. The append() function requires a CAS value. For more information on CAS values, see Section 7.4, “CAS get Methods”.

For example, to append a string to an existing key:

CASValue<Object> casv = client.gets("samplekey");
client.append(casv.getCas(),"samplekey", "appendedstring");

You can check if the append operation succeeded by using the return OperationFuture value:

OperationFuture<Boolean> appendOp =
    client.append(casv.getCas(),"notsamplekey", "appendedstring");

try {
    if (appendOp.get().booleanValue()) {
        System.out.printf("Append succeeded\n");
    }
    else {
        System.out.printf("Append failed\n");
    }
}
catch (Exception e) {
...
}

The second form of the append() method supports the use of custom transcoder.