Consistent read failure; rollback data not available
Oracle 无法构建一致性读映像，因为所需的撤销（回滚）数据已被覆盖。与 ORA-01555 类似，但发生在可序列化事务中。
SHOW PARAMETER undo_retention;SELECT tablespace_name, SUM(bytes)/1024/1024 mb FROM dba_data_files WHERE tablespace_name LIKE '%UNDO%' GROUP BY tablespace_name;SELECT * FROM v$undostat ORDER BY begin_time DESC FETCH FIRST 10 ROWS ONLY;