Re: functional call named notation clashes with SQL feature

On Wed, May 26, 2010 at 9:28 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
>> On Wed, May 26, 2010 at 8:21 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>>> If we go with the spec's syntax I think we'd have no realistic choice
>>> except to forbid => altogether as an operator name.  (And no, I'm not
>>> for that.)
>
>> I suppose the most painful thing about doing that is that it would
>> break hstore.  Are there other commonly-used modules that rely on =>
>> as an operator name?
>
> There don't seem to be any other contrib modules that define => as an
> operator name, but I'm not sure what's out there on pgfoundry or
> elsewhere.  The bigger issue to me is not so much hstore itself as that
> this is an awfully attractive operator name for anything container-ish.
> Wasn't the JSON-datatype proposal using => for an operator at one stage?
> (The current wiki page for it doesn't seem to reflect any such idea,
> though.)  And I think I remember Oleg & Teodor proposing such an
> operator in conjunction with some GIN-related idea or other.
>
>> In spite of the difficulties, I'm reluctant to give up on it.  I
>> always thought that the "AS" syntax was a crock and I'm not eager to
>> invent another crock to replace it.  Being compatible with the SQL
>> standard and with Oracle is not to be taken lightly.
>
> Yeah, I know.  Though this could end up being one of the bits of the
> spec that we politely decline to follow, like upper-casing identifiers.
> Still, it's a good idea to think again before we've set the release
> in stone ...

Perhaps one idea would be to:

1. Invent a new crock for now.
2. Add a duplicate version of the hstore => operator with a different name.
3. Emit a warning whenever an operator called => is created.
4. Document that beginning in PG 9.1, we will no longer support => as
an operator name.

That's still going to cause a fair amount of pain, but certainly less
if we decide it now rather than later.

--
Robert Haas
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