Re: Doc patch on psql output formats

Tom Lane wrote:

> > When a non-unique abbreviation is used, psql uses the first
> > match in an arbitrary order defined in do_pset() by
> > a cascade of pg_strncasecmp().
>
> Ugh. Should we not fix the code so that it complains if there's
> not a unique match? I would bet that the code was also written
> on the assumption that any abbrevation must be unique.

There's a backward compatibility issue, since a script issuing
\pset format a
would now fail instead of setting the format to "aligned".
The doc patch is meant to describe the current behavior.

OTOH if we don't fail with non-unique matches, there is the risk that
in the future, a new format matching /^a/ will come alphabetically
before "aligned", and will be picked up instead of "aligned".

In both cases using abbreviations in scripts is not a great
idea. Anyway I will look into the changes required in do_pset to
implement the error on multiple matches, if that's the preferred
behavior.

Best regards,
--
Daniel Vérité
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