Re: pgbench - allow backslash-continuations in custom scripts

On Sun, Mar 20, 2016 at 1:07 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
>> On Fri, Mar 18, 2016 at 10:02 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>>> This is mostly a flex/bison hack, isn't it? If you like I'll take it.
>
>> I would be delighted if you would.
>
> I've committed changes equivalent to Horiguchi-san's 0001 and 0002
> patches, though rather different in detail. I concur with the upthread
> opinion that 0003 doesn't seem really necessary.
>
> This solves the problem of allowing SQL commands in scripts to span
> lines, ...

Excellent.

> but it doesn't do anything about backslash commands, which was
> the original point according to the thread title ;-).

Wait, was it really? I'd been thinking it was mostly to continue
queries, not metacommands, but maybe I missed the boat.

> I can think of
> two somewhat-independent changes we might want to make at this point,
> since we're breaking exact script compatibility for 9.6 anyway:
>
> * Allow multiple backslash commands on one line, eg
> \set foo 5 \set bar 6
> The main reason for that is that psql allows it, and one of the things
> we're supposedly trying to do here is reduce the behavioral distance
> between psql and pgbench parsing rules.

This seems to me to be going in the wrong direction.

> * Allow backslash commands to span lines, probably by adopting the
> rule that backslash immediately followed by newline is to be ignored
> within a backslash command. This would not be compatible with psql,
> though, at least not unless we wanted to change psql too.

This might have some point to it, though, if you want to say \set i
<incredibly long expression not easily contained on a single line>

--
Robert Haas
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