Deadlocks due to update statements

Question

hi, we perform update statements as follows in the example below, with several threads each one mapping on a different connection as:
// THREAD operations
UPDATE table SET field=ThreadID WHERE field=default_value
COMMIT;
RESULTSET = SELECT pKey FROM table WHERE field=ThreadID;
... operations
// LOOP ON RESULTSET
WHILE RESULTSET.NEXT() NOT NULL;
UPDATE table SET field=default_Value WHERE PKEY=pKey;
COMMIT;
END WHILE;
// END LOOP
// END THREAD
Is a deadlock situation possible? Could this depend on particular settings of the configuration or connection?
Thanks a lot for the answers
null

Answer 1

hi aco,
deadlocks are possible only when you update a row (A)and not commit it and try to update a another row (B), and another process is trying to update row (B) and not commit and update row(A), so each process endup waiting for the other to release locks.
normally oracle does not let deadlocks in the database, if it detects deadlocks it rollbacks the statments itself with an error message.
since you seem to be commiting after an update there should not be a deadlock. unfortunately there are no settable parameters for lock issues. it is upto your application to prevent deadlocks. unless you use the facilities dbms_lock package or explicitly define your own locking mechanism for your application, you need not worry much about the deadlocks.
Mukundan.