查询死锁session的疑问？－－－查询很慢
select b.sid, b.serial#, b.machine, b.terminal, b.program, b.process, b.status
from v$lock a, v$session b
where a.sid = b.sid－－－查询较快
select sid, serial#, machine, terminal, program, process, status
from v$session
where sid in (select sid from v$lock)为什么会查询很慢呢？
select b.sid, b.serial#, b.machine, b.terminal, b.program, b.process, b.status
from v$lock a, v$session b
where a.sid = b.sid－－－查询较快
select sid, serial#, machine, terminal, program, process, status
from v$session
where sid in (select sid from v$lock)为什么会查询很慢呢？
详细的原因可以查看执行计划.