Here are three top concurrency problems in DB2. So DB2 use locking mechanism to avoid these.
DB2 Concurrency Problems
- Lost updates- Two processes A and B Accessing same row. A is updated the row, and then B also updates the same row. So A ‘s updates are lost.
- Dirty Read – Accessing data which is not committed
- Unrepeatable read- without concurrency causes you to get different data each time you read.
Because of all the above reasons, DB2 apply Locks on the resources.