On Tue, Sep 19, 2017 at 3:18 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Robert Haas <robertmhaas@gmail.com> writes:
>> I think the fact that single-target INTO lists and multiple-target
>> INTO lists are handled completely differently is extremely poor
>> language design. It would have been far better, as you suggested
>> downthread, to have added some syntax up front to let people select
>> the behavior that they want, but I think there's little hope of
>> changing this now without creating even more pain.
>
> How so? The proposal I gave is fully backwards-compatible. It's
> likely not the way we'd do it in a green field, but we don't have
> a green field.
>
>> I have a really hard time, however, imagining that anyone writes
>> SELECT a, b, c, d, e, f, g, h, i, j, k INTO x, y, z and wants some of
>> a-k to go into x, some more to go into y, and some more to go into z
>> (and heaven help you if you drop a column from x or y -- now the whole
>> semantics of the query change, yikes). What's reasonable is to write
>> SELECT a, b, c INTO x, y, z and have those correspond 1:1.
>
> That's certainly a case that we ought to support somehow. The problem is
> staying reasonably consistent with the two-decades-old precedent of the
> existing behavior for one target variable.
My point is that you objected to Pavel's proposal saying "it's not
clear whether users want A or B". But I think they always want A.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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