Re: Underscore in positional parameters?

On Sun, May 19, 2024 at 10:43 PM Erik Wienhold <ewie(at)ewie(dot)name> wrote:
>
> On 2024-05-19 07:00 +0200, Alexander Lakhin wrote:
> > I encountered anomalies that you address with this patch too.
> > And I can confirm that it fixes most cases, but there is another one:
> > SELECT $300000000 \bind 'foo' \g
> > ERROR: invalid memory alloc request size 1200000000
> >
> > Maybe you would find this worth fixing as well.
>
> Yes, that error message is not great. In variable_paramref_hook we
> check paramno > INT_MAX/sizeof(Oid) when in fact MaxAllocSize/sizeof(Oid)
> is the more appropriate limit to avoid that unspecific alloc size error.
>
> Fixed in v4 with a separate patch because it's unrelated to the param
> number parsing. But it fits nicely into the broader issue on the upper
> limit for param numbers. Note that $268435455 is still the largest
> possible param number ((2^30-1)/4) and that we just return a more
> user-friendly error message for params beyond that limit.
>

hi, one minor issue:

/* Check parameter number is in range */
if (paramno <= 0 || paramno > MaxAllocSize / sizeof(Oid))
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_PARAMETER),
errmsg("there is no parameter $%d", paramno),
parser_errposition(pstate, pref->location)));

if paramno <= 0 then "there is no parameter $%d" makes sense to me.

but, if paramno > 0 why not just say, we can only allow MaxAllocSize /
sizeof(Oid) number of parameters.