Re: Odd query execution behavior with extended protocol

Thanks for the help Tom and the others, I'll modify my sequence and report
if I encounter any further issues.

On Sun, Oct 4, 2015 at 7:36 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Shay Rojansky <roji(at)roji(dot)org> writes:
> >> To my mind there is not a lot of value in performing Bind until you
> >> are ready to do Execute. The only reason the operations are separated
> >> in the protocol is so that you can do multiple Executes with a row limit
> >> on each one, to retrieve a large query result in chunks.
>
> > 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.
>
> I think you might have more issues with lifespans, since portals go away
> at commit whereas named statements don't.
>
> regards, tom lane
>