Re: \gexec \watch

On 2018-Dec-06, Pavel Stehule wrote:

> čt 6. 12. 2018 v 12:26 odesílatel Oleksii Kliukin <alexk(at)hintbits(dot)com>
> napsal:

> > The other question is whether such a command would execute the original
> > query every time watch is invoked. Consider, e.g. the following one:
> >
> > select format('select now() as execution_time, %L as generation_time',
> > now()) \gexec
> > execution_time | 2018-12-06 12:15:24.136086+01
> > generation_time | 2018-12-06 12:15:24.13577+01
> >
> > If we make \gexec + \watch combination re-execute only the output of the
> > original query (without the query itself), then the generation time column
> > will stay constant through all \watch invocations.
>
> It is better to introduce new command like \gexec_repeat with units like
> 5s, or how much 5x -

It is? \gexec \watch is an elegant construct using two existing atoms
with well-defined semantics. Can't say I see that in \gexec_repeat --
it seems non-orthogonal to me.

To Oleksii's question, I think if you want to repeat the first query
over and over, you'd use something like this:

select format('select now() as execution_time, %L as generation_time', now()) as query \gset
:query \watch

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