Tom Lane wrote: > Bruce Momjian <[EMAIL PROTECTED]> writes: > > Could we allow slaves to check if the backend is still alive, perhaps by > > asking the postmaster, similar to what we do with the cancel signal --- > > that way, the slave would never time out and always wait if the master > > was alive. > > You're not considering the possibility of a transient communication > failure. The fact that you cannot currently contact the other guy > is not proof that he's not still alive. > > Example: > > Master Slave > ------ ----- > commit ready--> > <--OK > commit done->XX > > where "->XX" means the message gets lost due to network failure. Now > what? The slave cannot abort; he promised he could commit, and he does > not know whether the master has committed or not. The master does not > know the slave's state either; maybe he got the second message, and > maybe he didn't. Both sides are forced to keep information about the > open transaction indefinitely. Timing out on either side could yield > the wrong result.
Can't the master re-send the request after a timeout? -- Bruce Momjian | http://candle.pha.pa.us [EMAIL PROTECTED] | (610) 359-1001 + If your life is a hard drive, | 13 Roberts Road + Christ can be your backup. | Newtown Square, Pennsylvania 19073 ---------------------------(end of broadcast)--------------------------- TIP 8: explain analyze is your friend
