=?ISO-8859-2?Q?D=E1niel_D=E9nes?= <panther-d@xxxxxxxxxxx> writes: > But what if I try like >> SELECT * FROM mytable >> WHERE not_unique_col = 41 ORDER BY pri_key ASC FOR UPDATE; > and do the UPDATE after this? It should never lead to a deadlock, > assuming the rows selected FOR UPDATE are locked in the order as > they are returned. > But is that true? Are the rows selected FOR UPDATE locked in the same > order as they are returned (as specified in ORDER BY)? Should be all right --- the FOR UPDATE locking is always the last step in the SELECT pipeline. There's been some talk of pushing it down below a Limit step if any, to get rid of the rather unfortunate interaction of those two options ... but I don't see that we'd ever consider pushing it below a Sort. regards, tom lane
