AWR Report shows contention for 'row cache objects' as the top wait:
Top 5 Timed Foreground Events Event Waits Time(s) Avg wait (ms) DB time Wait Class latch: row cache objects 58,291,873 130,700 2 63.18 Concurrency DB CPU 60,563 29.27 db file sequential read 2,994,299 14,461 5 6.99 User I/O library cache lock 3,179 1,662 523 0.80 Concurrency gc cr grant 2-way 1,233,503 981 1 0.47 Cluster
对于latch相关的等待事件，我们可用通过awr的Latch Miss Sources发现在那个资源上有问题。
Latch Name Where NoWait Misses Sleeps Waiter Sleeps ... row cache objects kqrpre: find obj 0 10,332,326 8,906,124 row cache objects kqreqd: reget 0 7,888,165 8,503,625 row cache objects kqreqd 0 7,677,074 8,489,832 row cache objects kqrso 0 4,127 3,622 row cache objects kqrpre: init complete 0 143 88
mos搜索where条件获取有用的信息。