Using Fixed Binary

You can declare a fixed binary field using the BINARY() statement. When you do this, you must also specify the field's size in bytes. You then read and write the field value using Java byte arrays. However, if the byte array does not equal the specified size, then IllegalArgumentException is thrown when you attempt to write the field. Write the field value using a Java byte array.

If you want to store a large binary object, then you should use the LOB APIs rather than a binary field. For information on using the LOB APIs, see the Using the Large Object API.

Fixed binary should be used over the binary datatype any time you know that all the field values will be of the same size. Fixed binary is a more compact storage format because it does not need to store the size of the array. See Using Binary for information on the binary datatype.

To define a simple two-field table where the primary key is a UID and the second field contains a fixed binary field, you use the following DDL statement:

CREATE TABLE myTable (
    uid INTEGER,
    myByteArray BINARY(20),
    PRIMARY KEY (uid)
) 

DEFAULT and NOT NULL constraints are not supported for binary values.

To write the byte array, use Row.putFixed(). Again, if the byte array does not match the size defined for this field, then IllegalArgumentException is thrown.

TableAPI tableH = kvstore.getTableAPI();

Table myTable = tableH.getTable("myTable");

Row row = myTable.createRow();
row.put("uid", 12345);

String aString = "The quick brown fox.";
try {
    row.putFixed("myByteArray", aString.getBytes("UTF-8"));
} catch (UnsupportedEncodingException uee) {
    uee.printStackTrace();
}

tableH.put(row, null, null); 

To read the fixed binary field, use Row.get().asFixedBinary(). This returns a FixedBinaryValue class instance. You can then use FixedBinaryValue.get() to retrieve the stored byte array.

For example:

TableAPI tableH = kvstore.getTableAPI();

Table myTable = tableH.getTable("myTable");

/* Create a primary key for user id 12345 and get a row */
PrimaryKey key = myTable.createPrimaryKey();
key.put("uid", 12345);
Row row = tableH.get(key, null);

byte[] b = row.get("myByteArray").asFixedBinary().get();
String aString = new String(b);
System.out.println("aString: " + aString);