What are the Isolation level and uses of it

krbabu · New User Joined: 20 Feb 2004 Posts: 57

Can anybody give an idea of isolation level and uses of it

mdtendulkar · Active User Joined: 29 Jul 2003 Posts: 237 Location: USA

Hello krbabu,

Maintaining database consistency and data integrity, while allowing more than one application to access the same data at the same time, is known as concurrency. One of the ways DB2 attempts to enforce concurrency is through the use
of isolation levels, which determine how data used in one transaction is locked or isolated from other transactions while the first transaction accesses it. DB2 uses the following isolation levels to enforce concurrency:

Repeatable Read
Read Stability
Cursor Stability
Uncommitted Read

For more details on the same, refer the following link

www2.tw.ibm.com/developerWorks/tutorial/pdf/db2cert6v8-a4.pdf

Hope this helps,

Regards
Mayuresh Tendulkar

rachel · New User Joined: 09 Mar 2005 Posts: 13

Hi,

The contents of the tutorial are not in english.

anadhamohan · New User Joined: 27 Sep 2005 Posts: 25 Location: india

UR scans: No row locks are held unless row data is changing. It's Read-Only lock.
CS scans: Row locks are only held while the cursor is positioned on the row. Once the cursor moves from that row the lock will be released until the previous row is changed.
RS scans: Only qualifying row locks are held for the duration of the transaction. Others can able to view (or) insert rows to that page.
RR scans: All row locks are held for the duration of the transaction.

Cathy123 · New User Joined: 07 Jul 2006 Posts: 4 Location: Chennai

Hi,

Are Isolation levels different types of Row locks?

Thanks,
Cathy

vini_srcna · Posted: Wed Mar 21, 2007 1:45 pm

Isolation Level is different from Lock types.
Lock type (typically LOCKSIZE of ROW,TABLE,PAGE) says what kind of lock to hold.
It will be specified in the DDL of tablespace. I think it defaults to ANY which inturn says it ROW level locking.

Isolation level is to say How long to hold this lock. There are many articles on this concept.