Clarence Gardner <[EMAIL PROTECTED]> writes:
> I noticed the following in some of our code today:
>     select ... <join list> ... for update of a, b;

> Inasmuch as the cardinal rule for avoiding deadlocks is to acquire
> locks in a consistent order, should such a construction be avoided
> in favor of two separate "select ... for update" statements so that
> the order of acquisition of a and b is known?

If you're worried about deadlock, what you should be worrying about is
the order in which the individual rows are visited --- and splitting
this into two SQL commands doesn't in itself guarantee more about that
than the command as given.

                        regards, tom lane

---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
       choose an index scan if your joining column's datatypes do not
       match

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