Re: psql - add SHOW_ALL_RESULTS option

On Thu, Jan 16, 2020 at 01:08:16PM -0500, Tom Lane wrote:
>Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com> writes:
>> This is one of the patches already marked as RFC (since September by
>> Alvaro). Anyone interested in actually pushing it, so that it does not
>> fall through to yet another commitfest?
>
>TBH, I think we'd be better off to reject it. This makes a nontrivial
>change in a very long-standing psql behavior, with AFAICS no way to
>get back the old semantics. (The thread title is completely misleading
>about that; there's no "option" in the patch as it stands.) Sure,
>in a green field this behavior would likely be more sensible ... but
>that has to be weighed against the fact that it's behaved the way it
>does for a long time, and any existing scripts that are affected by
>that behavior have presumably deliberately chosen to use it.
>
>I can't imagine that changing this will make very many people happier.
>It seems much more likely that people who are affected will be unhappy.
>
>The compatibility issue could be resolved by putting in the option
>that I suppose was there at the beginning. But then we'd have to
>have a debate about which behavior would be default, and there would
>still be the question of who would find this to be an improvement.
>If you're chaining together commands with \; then it's likely that
>you are happy with the way it behaves today. Certainly there's been
>no drumbeat of bug reports about it.
>

I don't know, really, I only pinged this as a CFM who sees a patch
marked as RFC for months ...

The current behavior certainly seems strange/wrong to me - if I send
multiple queries to psql, I'd certainly expect results for all of them,
not just the last one. So the current behavior seems pretty surprising.

I'm unable to make any judgments about risks/benefits of this change. I
can't imagine anyone intentionally relying on the current behavior, so
I'd say the patch is unlikely to break anything (which is not already
broken). But I don't have any data to support this ...

Essentially, I'm just advocating to make a decision - we should either
commit or reject the patch, not just move it to the next commitfest over
and over.

regards

--
Tomas Vondra http://www.2ndQuadrant.com
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