您的数据库之一支持OLTP工作负载。 默认的UNDO表空间是固定大小的，具有： 1. RETENTION NOGUARANTEE 2. UNDO_RETENTION是12分钟 在销售表上的查询运行超过15分钟后，用户SCOTT收到此错误：ORA-01555：snapshot too old 分别或组合使用的三个因素可能是原因？ 在查询开始前超过12分钟对SALES表进行了提交更新。 在查询开始前超过12分钟对SALES表进行了删除。 在查询开始之前已对SALES表进行了更新。 ？？ One of your databases supports an OLTP workload. The default undo tablespace is fixed size with: RETENTION NOGUARANTEE undo_retention is 12 minutes User scott get this error after a query on the sales table has run for more than 15 minutes: ORA-01555: snapshot too old Which three factors taken separately or in some combination might be the cause? A) A committed delete to the sales table was made more than 12 minutes before the query began. C) A committed update to the sales table was made more than 12 minutes before the query began. F) An update to the SALES table was committed after the query began. Answer：ACF