Oracle Database Discussions

I have gone thruough oracle documentation(http://docs.oracle.com/cd/B10500_01/server.920/a96524/c21cnsis.htm#2641) regarding the lock mechanism and have understood that

Select * from hr.locations for update;

should acquire RS table lock and X row lock on hr.locations.

But When I execute the below statement to check it:

Select Session_id SID,lock_type,mode_held from dba_locks where session_id =147;

I am getting the below output:

SID     Lock_type    mode_held
147	AE	        Share
147	DML          	Row-X (SX)
147	Transaction	Exclusive

i.e it is acquiring Row exclusive lock.

Please clarify my doubt and also I wasnt able to understand about AE lock_type.

VERSION:Oracle Database 11g Enterprise Edition Release 11.1.0.7.0

Thanks

Edited by: user650693 on 05-Feb-2012 12:01