Hello all,

I know that Oracle uses undo table spaces or rollback segments as its undo mechanism. what does DB2 use as its undo mechanism?

Krz

in db2 there is a mechanism of pages in the buffer and the log file - this is the only area needed.
Best Regards, Guy Przytula

Oracle uses undo table spaces or rollback segments not just as its rollback mechanism, but also to provide support for different isolation levels; If you have a transaction, with isolation level RR, if you read a table with 5000 records, even if you choose 2 records, you lock 5000 records and may be it will be escalated to a table lock, in DB2. Oracle will use undo. For a simple rollback, log files will suffice, because each record has before and after a change INFO.