What Is a Dead Lock


What Is a Dead Lock? - Oracle DBA FAQ - Understanding SQL Transaction Management

✍: FYIcenter.com


A dead lock is phenomenon happens between two transactions with each of them holding a lock that blocks the other transaction as shown in the following diagram:

(transaction 1)                (transaction 2)
update row X to create lock 1
                               update row Y to create lock 2
                               update row X
                               (blocked by lock 1)
update row Y
(blocked by lock 2)

(dead lock created)

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