Re: \watch 0 or \watch 0.00001 doesn't do what I want

Heikki Linnakangas <hlinnaka@iki.fi>

From: Heikki Linnakangas <hlinnaka@iki.fi>
To: "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Cc: Daniel Gustafsson <daniel@yesql.se>
Date: 2024-10-09T13:59:35Z
Lists: pgsql-hackers
On 09/10/2024 16:38, Heikki Linnakangas wrote:
> Daniel's post [1] on \watch reminded me of this little issue I bumped into:
> 
> I wanted to run a query in a tight loop, without any delay. I tried 
> "\watch 0", but it didn't do what I wanted:
> 
> postgres=# \watch 0

Correction: This changed in version 16. It works the way I expected on 
v16, but not in earlier versions.

> Then I tried setting the delay really small, but that didn't do what I wanted either:
> 
> postgres=# \watch 0.00001
> Wed 09 Oct 2024 16:36:45 EEST (every 1e-05s)
> 
>  ?column?
> ----------
>         1
> (1 row)
> 
> ^C
> 
> It runs the query just once and then hangs forever, until I hit CTRL-C to cancel.

This issue is present on newer versions still.

-- 
Heikki Linnakangas
Neon (https://neon.tech)




Commits

  1. psql: Fix \watch when using interval values less than 1ms