Re: checking variadic "any" argument in parser - should be array

Hi Pavel,

I had a look over your new patch and it looks good to me.

My review comments on patch:

1. It cleanly applies with patch -p1 command.
2. make/make install/make check were smooth.
3. My own testing didn't find any issue.
4. I had a code walk-through and I am little bit worried or confused on
following changes:

if (PG_ARGISNULL(argidx))
return NULL;

! /*
! * Non-null argument had better be an array. The parser doesn't
! * enforce this for VARIADIC ANY functions (maybe it should?), so
that
! * check uses ereport not just elog.
! */
! arr_typid = get_fn_expr_argtype(fcinfo->flinfo, argidx);
! if (!OidIsValid(arr_typid))
! elog(ERROR, "could not determine data type of concat()
input");
!
! if (!OidIsValid(get_element_type(arr_typid)))
! ereport(ERROR,
! (errcode(ERRCODE_DATATYPE_MISMATCH),
! errmsg("VARIADIC argument must be an array")));

- /* OK, safe to fetch the array value */
arr = PG_GETARG_ARRAYTYPE_P(argidx);

/*
--- 3820,3828 ----
if (PG_ARGISNULL(argidx))
return NULL;

! /* Non-null argument had better be an array */
!
Assert(OidIsValid(get_element_type(get_fn_expr_argtype(fcinfo->flinfo,
argidx))));

arr = PG_GETARG_ARRAYTYPE_P(argidx);

We have moved checking of array type in parser (ParseFuncOrColumn()) which
basically verifies that argument type is indeed an array. Which exactly same
as that of second if statement in earlier code, which you replaced by an
Assert.

However, what about first if statement ? Is it NO more required now? What if
get_fn_expr_argtype() returns InvalidOid, don't you think we need to throw
an error saying "could not determine data type of concat() input"?

Well, I tried hard to trigger that code, but didn't able to get any test
which fails with that error in earlier version and with your version. And
thus I believe it is a dead code, which you removed ? Is it so ?

Moreover, if in any case get_fn_expr_argtype() returns an InvalidOid, we
will hit an Assert rather than an error, is this what you expect ?

5. This patch has user visibility, i.e. now we are throwing an error when
user only says "VARIADIC NULL" like:

select concat(variadic NULL) is NULL;

Previously it was working but now we are throwing an error. Well we are now
more stricter than earlier with using VARIADIC + ANY, so I have no issue as
such. But I guess we need to document this user visibility change. I don't
know exactly where though. I searched for VARIADIC and all related
documentation says it needs an array, so nothing harmful as such, so you can
ignore this review comment but I thought it worth mentioning it.

Thanks

On Thu, Jun 27, 2013 at 12:35 AM, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>wrote:

> Hello
>
> remastered version
>
> Regards
>
> Pavel
>
> 2013/6/26 Jeevan Chalke <jeevan(dot)chalke(at)enterprisedb(dot)com>:
> > Hi Pavel
> >
> >
> > On Sat, Jan 26, 2013 at 9:22 AM, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
> > wrote:
> >>
> >> Hello Tom
> >>
> >> you did comment
> >>
> >> ! <----><------><------> * Non-null argument had better be an array.
> >> The parser doesn't
> >> ! <----><------><------> * enforce this for VARIADIC ANY functions
> >> (maybe it should?), so
> >> ! <----><------><------> * that check uses ereport not just elog.
> >> ! <----><------><------> */
> >>
> >> So I moved this check to parser.
> >>
> >> It is little bit stricter - requests typed NULL instead unknown NULL,
> >> but it can mark error better and early
> >
> >
> > Tom suggested that this check should be better done by parser.
> > This patch tries to accomplish that.
> >
> > I will go review this.
> >
> > However, is it possible to you to re-base it on current master? I can't
> > apply it using "git apply" but patch -p1 was succeeded with lot of
> offset.
> >
> > Thanks
> >
> >>
> >>
> >> Regards
> >>
> >> Pavel
> >>
> >>
> >> --
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> >
> >
> >
> > --
> > Jeevan B Chalke
> > Senior Software Engineer, R&D
> > EnterpriseDB Corporation
> > The Enterprise PostgreSQL Company
> >
> > Phone: +91 20 30589500
> >
> > Website: www.enterprisedb.com
> > EnterpriseDB Blog: http://blogs.enterprisedb.com/
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--
Jeevan B Chalke
Senior Software Engineer, R&D
EnterpriseDB Corporation
The Enterprise PostgreSQL Company

Phone: +91 20 30589500

Website: www.enterprisedb.com
EnterpriseDB Blog: http://blogs.enterprisedb.com/
Follow us on Twitter: http://www.twitter.com/enterprisedb

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