RE: Locking

From: <>
Date: Thu, 17 Nov 2011 15:31:56 -0500
Message-ID: <>

Also, there is an excellent discussion of this in Tom Kytes, expert oracle database architecture book. Topics include such things as comparing Transaction Isolation Levels between some DBMS's, locking, and concurrency.

A great book for developers, (and DBA's).

Transaction Isolation Levels -- Read uncommitted, read committed, repatable read, serializable, read only...

Joel Patterson
Database Administrator
904 727-2546

-----Original Message-----

From: [] On Behalf Of Paul Harrison Sent: Thursday, November 17, 2011 2:53 PM To:
Subject: Locking

Hi All,

Let's say I have 2 sessions open... session one updates a table and does not commit and can view the new updated data. session 2 is able to read the old data. How can session 2 read the old data if session 1 has an exclusive write lock on the table. Exclusive lock happens when updating a table?



-- Received on Thu Nov 17 2011 - 14:31:56 CST

Original text of this message