rollback segment短语⁹⁶⁶⁷⁷⁺⁶ 基本例句 回滚段 Therefore, ORA-01555 will result if the query is looking for the snapshot which is so old that rollback segment information could not be found because of wrap around or overwrite. 就是说，导致 ORA-01555的原因其实就是：快照在该查询执行过程中被修改了清除或者覆盖。 ppmiao.com