On Tue, Feb 08, 2005 at 12:58:34AM -0500, Tom Lane wrote: > Michael Fuhr <mike@xxxxxxxx> writes: > > > > I think you can infer that a process is working with a row in some > > manner (UPDATE, SELECT FOR UPDATE) by looking at the row's xmax > > column and checking pg_locks to see if any process is holding a > > lock on the indicated transaction ID. > > I'm too tired to work out an example, but I think this probably doesn't > work in general: the xmax on the version of the row you can see might > not correspond to a live transaction, but that doesn't mean someone > else doesn't hold a lock on the latest committed version of the row. Okay...I had done some tests with UPDATE and SELECT FOR UPDATE and observed what I wrote, but admittedly that covers only a few cases. If you could point me in the right direction I'll try to work out an example where my suggestion fails. -- Michael Fuhr http://www.fuhr.org/~mfuhr/ ---------------------------(end of broadcast)--------------------------- TIP 7: don't forget to increase your free space map settings
