This event occurs when a session requests a buffer that is currently being read into the buffer cache 
by another session. Prior to release 10.1, waits for this event were grouped with the other reasons for 
waiting for buffers under the 'buffer busy wait' event

Top 5 Timed Events                                        Avg %Total
~~~~~~~~~~~~~~~~~~                                        wait  Call
Event                                Waits    Time (s)  (ms)  Time Wait Class
------------------------------ ------------ ----------- ------ ------ ----------
CPU time                                          4,897          52.9
db file sequential read          1,557,308      1,887      1  20.4  User I/O
read by other session            3,818,768      1,769      0  19.1  User I/O
db file scattered read              973,678        807      1    8.7  User I/O

log file sync    

可通過如下SQL語句查看競爭的數(shù)據(jù)塊：

SELECT p1 “file#”,p2 “block#”,p3 “class#” FROM v$session_wait WHERE event = 'read by other session';