> > > So you would suggest changing my message chain to send Bind right after > > Execute, right? This would yield the following messages: > > > P1/P2/D1/B1/E1/D2/B2/E2/S (rather than the current > > P1/D1/B1/P2/D2/B2/E1/C1/E2/C2/S) > > > This would mean that I would switch to using named statements and the > > unnamed portal, rather than the current unnamed statement > > and named portals. If I recall correctly, I was under the impression that > > there are some PostgreSQL performance benefits to using the > > unnamed statement over named statements, although I admit I can't find > any > > documentation backing that. Can you confirm that the two > > are equivalent performance-wise? > > Hmm. I do not recall exactly what performance optimizations apply to > those two cases; they're probably not "equivalent", though I do not think > the difference is major in either case. TBH I was a bit surprised on > reading your message to hear that the system would take that sequence at > all; it's not obvious that it should be allowed to replace a statement, > named or not, while there's an open portal that depends on it. >
One more important piece of information... The reason Npgsql currently sends P1/D1/B1/P2/D2/B2/E1/C1/E2/C2/S is to avoid deadlocks, I've already discussed this with you in http://www.postgresql.org/message-id/cadt4rqb+fbtqpte5ylz0hkb-2k-ngzhm2ybvj0tmc8rqbgf...@mail.gmail.com . Unfortunately, the alternative I proposed above, P1/P2/D1/B1/E1/D2/B2/E2/S, suffers from the same issue: any sequence in which a Bind is sent after a previous Execute is deadlock-prone - Execute causes PostgreSQL to start writing a potentially large dataset, while Bind means the client may be writing a potentially large parameter value. In other words, unless I'm mistaken it seems there's no alternative but to implement non-blocking I/O at the client side - write until writing would block, switching to reading when that happens. This adds some substantial complexity, especially with .NET's SSL/TLS implementation layer. Or does anyone see some sort of alternative which I've missed?
