Re: Document parameter count limit

On Thu, Oct 26, 2023 at 3:51 PM Bruce Momjian <bruce(at)momjian(dot)us> wrote:

> On Wed, Nov 23, 2022 at 02:33:27PM -0600, Justin Pryzby wrote:
> > On Wed, Nov 23, 2022 at 12:35:59PM -0700, David G. Johnston wrote:
> > > On Wed, Nov 23, 2022 at 11:47 AM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> > >
> > > > Bruce Momjian <bruce(at)momjian(dot)us> writes:
> > > > > Does this come up enough to document it? I assume the error
> message the
> > > > > user receives is clear.
> > > >
> > > > Looks like you get
> > > >
> > > > if (nParams < 0 || nParams > PQ_QUERY_PARAM_MAX_LIMIT)
> > > > {
> > > > libpq_append_conn_error(conn, "number of parameters must be
> between 0 and %d",
> > > > PQ_QUERY_PARAM_MAX_LIMIT);
> > > > return 0;
> > > > }
> > > >
> > > > which seems clear enough.
> > > >
> > > > I think the concern here is that somebody who's not aware that a
> limit
> > > > exists might write an application that thinks it can send lots of
> > > > parameters, and then have it fall over in production. Now, I've got
> > > > doubts that an entry in the limits.sgml table will do much to prevent
> > > > that scenario. But perhaps offering the advice to use an array
> parameter
> > > > will be worthwhile even after-the-fact.
> >
> > Yes, that's what happens :)
> >
> > I hit that error after increasing the number of VALUES(),() a loader
> > used in a prepared statement (and that was with our non-wide tables).
> >
> > +1 to document the limit along with the other limits.
>
> Here is a patch to add this.
>
>
We aren't talking about "function arguments" though...is there something
wrong with the term "parameters per query"?

I suggest we take this opportunity to decide how to handle values > 999 in
terms of separators. The existing page is inconsistent. I would prefer
adding the needed commas.

David J.