Re: psql FETCH_COUNT feature does not work with combined queries

On 2020-Jul-16, David Johnston wrote:

> Instead of a note maybe add a paragraph stating:
> 
> "This setting is ignored when multiple statements are sent to the server as a single command (i.e., via the -c
commandline option or the \; meta-command).  Additionally, it is possible for certain combinations of statements sent
inthat manner to instead return no results, or even be ignored, instead of returning the result set of the last query.
Inshort, when FETCH_COUNT is non-zero, and you send a multi-statement command to the server, the results are undefined.
Thiscombination in presently allowed for backward compatibility."
 

I personally dislike documenting things that don't work, if worded in a
way that don't leave open the possibility of fixing it in the future.
So I didn't like Fabien's original wording either, though I was thinking
that just adding "This may change in a future release of Postgres" might
have been enough.  That seems more difficult with your proposed wording,
but maybe you see a good way to do it?

After rereading it a few times, I think it's too specific about how it
fails.  Maybe it's possible to reduce to just the last two phrases,
along the lines of

> When FETCH_COUNT is non-zero, and you send a multi-statement command
> to the server (for example via -c or the \; meta-command), the results
> are undefined. This combination in presently allowed for backward
> compatibility and may be changed in a future release.

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
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