Snapshot too old
查询或事务需要的 undo 数据已被覆盖，因为 undo 保留时间不足以支持操作持续时间。
SHOW PARAMETER undo;SELECT tablespace_name, SUM(bytes)/1024/1024 size_mb FROM dba_data_files WHERE tablespace_name LIKE '%UNDO%' GROUP BY tablespace_name;SELECT begin_time, end_time, tuned_undoretention FROM v$undostat ORDER BY begin_time DESC FETCH FIRST 5 ROWS ONLY;