ORA-01555：snapshot too old: rollback segment number X with name "XXXX" too small

ORA-01555：snapshot too old: rollback segment number X with name "XXXX" too small

在查询快照的时候

select * from testtable as of timestamp to_timestamp('2023-04-03 22:00:00','yyyy-mm-dd hh24:mi:ss')

提示错误 ORA-01555：snapshot too old: rollback segment number X with name "XXXX" too small

简单来说，就是数据库的undo_retention设置的太小了

调大以后对于后面的闪回数据量的限制就不会那么大了