On Thu, 2010-10-21 at 10:29 -0500, Kevin Grittner wrote: > Basically, when we already have a pivot, but no transaction has yet > committed, we wait to see if TN commits first. If so, we have a > problem; if not, we don't. There's probably some room for improving > performance by cancelling T0 or T1 instead of TN, at least some of > the time; but in this pass we are always cancelling the transaction > in whose process we detect the need to cancel something.
Well, in this case we do clearly have a problem, because the result is not equal to the serial execution of the transactions in either order. So the question is: at what point is the logic wrong? It's either: 1. PreCommit_CheckForSerializationFailure() is missing a failure case. 2. The state prior to entering that function (which I believe I sufficiently described) is wrong. If it's (2), then what should the state look like, and how is the GiST code supposed to result in that state? I know some of these questions are answered in the relevant research, but I'd like to discuss this concrete example specifically. Regards, Jeff Davis -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers