Re: strange IS NULL behaviour

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Bruce Momjian <bruce(at)momjian(dot)us>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Hannu Krosing <hannu(at)2ndquadrant(dot)com>, Peter Eisentraut <peter_e(at)gmx(dot)net>, Andrew Dunstan <andrew(at)dunslane(dot)net>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: strange IS NULL behaviour
Date: 2013-09-05 16:57:59
Message-ID: CA+TgmoYyQLULM_kCWE39edzMq6KiNPEzPChGGO2a9a=VAOZP2Q@mail.gmail.com
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On Wed, Sep 4, 2013 at 9:26 PM, Bruce Momjian <bruce(at)momjian(dot)us> wrote:
> On Tue, Sep 3, 2013 at 09:32:44PM -0400, Bruce Momjian wrote:
>> In this test, SELECT NULL (which internally would produce SELECT
>> ROW(NULL)), returns TRUE, while SELECT ROW(NULL) and further nesting
>> returns false.
>>
>> This has made me adjust my goal and change it so SELECT ROW(NULL) IS
>> NULL returns true, and any further nesting returns false.
>>
>> Attached is a patch which accomplishes this, and a documentation update.
>
> I have not heard any feedback on this patch, so I would like to apply it
> to give us a nested ROW/IS NULL API we can document. It would have to
> be marked in the release notes as a backward incompatibility.

I don't have time to look at this in detail right now, but I think
that's considerably premature. I'm not convinced that we understand
all of the problems in this area are yet, let alone the solutions.
And I notice that you haven't substantively responded to some of Tom's
concerns.

So -1 from me.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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