ORA-08186: invalid timestamp specified

1、

SQL> select count(*) from t as of timestamp to_timestamp('2015-05-20 12:00:00','YYYY-MM-DD HH24:MI:SS');
select count(*) from t as of timestamp to_timestamp('2015-05-20 12:00:00','YYYY-MM-DD HH24:MI:SS')
                     *
ERROR at line 1:
ORA-08186: invalid timestamp specified

SYSDATE
-------------------
2015-05-20 02:13:28

如果指定一个未来的时间就会报以上的错误

2、

SQL> select count(*) from t as of timestamp to_timestamp('2015-05-19 12:00:00','YYYY-MM-DD HH24:MI:SS');
select count(*) from t as of timestamp to_timestamp('2015-05-19 12:00:00','YYYY-MM-DD HH24:MI:SS')
                     *
ERROR at line 1:
ORA-01466: unable to read data - table definition has changed

报错的原因，是因为在该时间点，表还没有创建

SQL>  select count(*) from t as of timestamp to_timestamp('2015-05-20 02:00:00','YYYY-MM-DD HH24:MI:SS');

  COUNT(*)
----------
     72511