设置参数解决
alter system set "_smu_debug_mode"=33554432;
设置这个之后v$undostat.tuned_undoretention会取(maxquerylen secs + 300)和参数undo_retention里的最大值
alter system set "_undo_autotune"=false;
直接禁用了Automatic Tuning of Undo Retention特性
alter system set "_HIGHTHRESHOLD_UNDORETENTION"=900;
设置UNDORETENTION保留时间
High Undo Space Usage Due to Query 0rc4km05kgzb9 (Doc ID 2584684.1)