Re: Variable substitution in psql backtick expansion

2017-03-31 15:00 GMT+02:00 Daniel Verite <daniel(at)manitou-mail(dot)org>:

> Tom Lane wrote:
>
> > Thoughts?
>
> ISTM that expr is too painful to use to be seen as the
> idiomatic way of achieving comparison in psql.
>
> Among its disadvantages, it won't work on windows, and its
> interface is hard to work with due to the necessary
> quoting of half its operators, and the mandatory spacing
> between arguments.
>
> Also the quoting rules and command line syntax
> depend on the underlying shell.
> Isn't it going to be tricky to produce code that works
> across different families of shells, like bourne and csh?
>
> I think that users would rather have the option to just put
> an SQL expression behind \if. That implies a working connection
> to evaluate, which expr doesn't, but that's no
> different from the other backslash commands that read
> the database.
>

some basic expression can be done on client side like defvar, serverver,
... but generic expression should be evaluated in server - I am not sure,
if it is what we would - when I have PLpgSQL.

In psql scripting I expecting really simple expressions - but it should to
work everywhere - using bash is not good enough.

Regards

Pavel

>
>
> Best regards,
> --
> Daniel Vérité
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