public static HiveOperation operationForToken(int token) {
    return TOKEN_TO_OPERATION.get(token);
  }
Only a small set of operations is allowed inside an explicit transactions, e.g. DML on
Acid tables or ops w/o persistent side effects like USE DATABASE, SHOW TABLES, etc so
that rollback is meaningful
todo: mark all operations appropriately
ql/src/java/org/apache/hadoop/hive/ql/plan/HiveOperation.java