Re: pgsql: Add libpq pipeline mode support to pgbench

Bonjour Daniel, Ola Alvaro,

> Add libpq pipeline mode support to pgbench
>
> New metacommands \startpipeline and \endpipeline allow the user to run
> queries in libpq pipeline mode.
>
> Author: Daniel Vérité <daniel(at)manitou-mail(dot)org>
> Reviewed-by: Álvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>
> Discussion: https://postgr.es/m/b4e34135-2bd9-4b8a-94ca-27d760da26d7@manitou-mail.org

I did not notice that the libpq pipeline mode thread had a pgbench patch
attached, otherwise I would have looked at it.

Some minor post-commit comments:

For consistency with the existing \if … \endif, ISTM that it could have
been named \batch … \endbatch or \pipeline … \endpipeline?

ISTM that the constraint checks (nesting, no \[ag]set) could be added to
CheckConditional that could be renamed to CheckScript. That could allow to
simplify the checks in the command execution as mere Asserts.

--
Fabien.