On Mon, Jun 06, 2005 at 09:21:15AM -0400, Douglas McNaught wrote: > "Surabhi Ahuja " <surabhi.ahuja@xxxxxxxxxxx> writes: > > > say i have two transactions going on simultaneoulsy. > > in one transaction i do an insertion > > and the other transaction i do a delete. > > what will happen if in both the transactions, the insert(in one) and > > delete(in the other) are issued at exactly the same time? will bothe get > > blocked and enter into a deadlock, if yes then do both the transactions > > get aborted after some time of waiting. > > The transactions will be executed completely independently, unless you > do explicit locking (via SELECT FOR UPDATE or LOCK TABLE). Deadlock can still happen if Transaction A's INSERT blocks because of something Transaction B did previously, and Transaction B's DELETE blocks because of something Transaction A did previously. Foreign key relationships are a typical cause, but even UPDATEs on simple tables can cause later operations to deadlock if the application isn't careful with its order of operations. -- Michael Fuhr http://www.fuhr.org/~mfuhr/ ---------------------------(end of broadcast)--------------------------- TIP 4: Don't 'kill -9' the postmaster
