Re: \watch stuck on execution of commands returning no tuples

From: Michael Paquier <michael(dot)paquier(at)gmail(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: PostgreSQL mailing lists <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: \watch stuck on execution of commands returning no tuples
Date: 2013-05-03 01:04:04
Message-ID: CAB7nPqTcR+9U+mJUkVTrKBZp-P+qyo=iE-93-uYYa5LHeTx0Pg@mail.gmail.com
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On Thu, May 2, 2013 at 11:01 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Michael Paquier <michael(dot)paquier(at)gmail(dot)com> writes:
> > Hi all,
> > When testing \watch, I noticed that process waits indefinitely when
> > executing it with a DDL or a DML.
> > For example:
> > postgres=# CREATE TABLE aa (a int);
> > postgres=# ANALYSE aa \watch 10
> > -- Process waiting here
>
> It's not "waiting", it's doing the ANALYZE once every ten seconds,
> just like you told it to.
>
> Perhaps it'd be a good idea to emit the command tag on receiving a
> non-tuple-bearing result, just to make this more obvious.
>
Yes, the command tag would be a good idea, combined with the watch time
that other commands returning tuples have, giving something like that:
Watch every 2s Fri May 3 10:01:04 2013
$TAG

Regards,
--
Michael

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