}
// create a Schema object containing the give column
private Schema getSchema() {
Schema sch = new Schema();
FieldSchema tmpFieldSchema = new FieldSchema();
tmpFieldSchema.setName(SET_COLUMN_NAME);
tmpFieldSchema.setType(STRING_TYPE_NAME);
sch.putToProperties(SERIALIZATION_NULL_FORMAT, defaultNullString);
sch.addToFieldSchemas(tmpFieldSchema);
return sch;
}