How get outside deadlock

Question

Hi all,
i have these problem i get one "cool" app on my table which has these feature. Have deadlock problem ;). There occur situation when one sesion is select for update row with id = 10 second session take for update 20 first want take 20 then ;) and second 10 :0 and deadlock is born.
oracle find deadlock and one select is raising exception e.g.
S2 take 20
S1 take 10
S1 try take 20 and waitin
S2 try take 10 = deadlock
oracle throw error in S1
and my goal is catch this exception and try do same work in S1 again i try something like this (pseudocode)
while deadlock = true loop
deadlock := false;
savepoint s1
begin
select for update where id = 10;
select for update where id = 20;
exception
when others then
if errorcode = - 60 then deadlock :- true rollback to s1;
end;
end loop
but rollback to savepoint dont unlock my rows. can u give me advice how make this on oracle? I want loop in which i can free all my locks.
Thanks a lot martin.

Answer 1

Is there a reason that you can't simply avoid the deadlock by requiring that sessions lock rows in a particular order (i.e. always lock row 10 before trying to lock row 20)? Or that you can't specify NOWAIT when you try to lock the row and handle the ORA-00054 error if the row is already locked? Normally, the solution to deadlock problems is not to allow them to occur, not to try to handle them when they occur.
Justin