Re: Underscore in positional parameters?

On 2024-05-20 03:26 +0200, jian he wrote:
> On Sun, May 19, 2024 at 10:43 PM Erik Wienhold <ewie@ewie.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.

Yes, it makes sense to show the upper bound.  How about a hint such as
"Valid parameters range from $%d to $%d."?

-- 
Erik