Robert Haas <robertmh...@gmail.com> writes: > On Mon, Apr 25, 2016 at 12:16 PM, Shay Rojansky <r...@roji.org> wrote: >> Sure. I'd consider sending in a patch, but as this is a protocol-changing >> feature it seems like working on this before the team "officially" starts >> working on a new protocol might be a waste of time. Once there's critical >> mass for a new protocol and agreement that PostgreSQL is going for it I'd be >> happy to work on it.
> I don't immediately see a reason why this couldn't be done as an > isolated change. Suppose that we change the server to allow a cancel > request to be either 16 bytes or 20 bytes, rather than always 16 bytes > as they are currently. Clients will need to be careful not to send > the new type of cancel request to a server that is too old to > understand it, but since they've got an active connection, > server_version will have been previously reported. > More generally, as long as new protocol bits are client-initiated, I > don't think we really need to bump the protocol version. If we want > to change the kinds of responses the server sends or structurally > change the format of protocol messages or deprecate messages that > exist now, then we do. Meh --- I'm fairly suspicious of shoehorning things in and pretending it's not a protocol change. That usually leads to crufty and ultimately unmaintainable designs, because you're forced to do strange things when you do it that way. (Cf the COPY RAW thread for a recent example.) Having said that, CANCEL is sufficiently outside the normal protocol that maybe you are right: we could invent what amounts to a new cancel protocol and trust clients to look at server_version to know what to send. One problem is that we really ought to widen the random cancel key while we're at it; 32 bits doesn't seem like enough to prevent brute-force searches anymore. However, since the cancel key is transmitted from the server within the normal protocol, I don't see any way to do that without a compatibility break. Is there anything else people have complained about w.r.t. CANCEL? regards, tom lane -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers