if(pkFieldName == null)
{
throw new DatabusException("No primary key specified in the schema");
}
PrimaryKeySchema pkSchema = new PrimaryKeySchema(pkFieldName);
List<Schema.Field> fields = schema.getFields();
List<KeyPair> kpl = new ArrayList<KeyPair>();
int cnt = 0;
for(Schema.Field field : fields)
{
if (pkSchema.isPartOfPrimaryKey(field))
{
o = cl.get(cnt).getValue();
st = field.schema().getType();
KeyPair kp = new KeyPair(o, st);
kpl.add(kp);