Re: \gexec \watch

Alvaro Herrera wrote:

> Honestly, I don't see the mathematicality in this. It either works, or
> it doesn't -- and from my POV right now it doesn't. Are you saying we
> need a \gexecwatch for this to work?
>
> I can of course solve my problem with a simple python program, but psql
> is so close ...

\watch reexecutes what's in the query buffer, and \gexec does not
write into the query buffer, so the desired piping does not happen
by design.

I think you could achieve more or less the result with a pre-gexec
hack like that:

postgres=# \pset tuples_only on
postgres=# select 'select now();' \g /tmp/file.sql
postgres=# \setenv EDITOR touch
postgres=# \e /tmp/file.sql
2018-12-06 13:54:24.915752+01

postgres=# \watch
2018-12-06 13:54:42.366559+01

2018-12-06 13:54:44.368962+01

2018-12-06 13:54:46.3713+01

....

The "\setenv EDITOR touch" kludge is meant to force \e to
inject the contents of /tmp/file.sql into the query buffer.
It's needed because "\e file" actually checks whether the file has
been modified (per mtime) after $EDITOR returns, and discards it
if it hasn't.

Best regards,
--
Daniel Vérité
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