Re: psql \watch versus \timing

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
Cc: pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: psql \watch versus \timing
Date: 2013-05-19 22:33:52
Message-ID: 10853.1369002832@sss.pgh.pa.us
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Jeff Janes <jeff(dot)janes(at)gmail(dot)com> writes:
> I'd like to run same query repeatedly and see how long it takes each time.
> I thought \watch would be excellent for this, but it turns out that using
> \watch suppresses the output of \timing.

> Is this intentional, or unavoidable?

\watch uses PSQLexec not SendQuery; the latter implements \timing which
I agree is arguably useful here, but also autocommit/auto-savepoint
behavior which probably isn't a good idea.

It might be a good idea to refactor those two routines into one routine
with some sort of bitmap flags argument to control the various add-on
behaviors, but that seems like not 9.3 material anymore.

> Also, is it just or does the inability to watch more frequently than once a
> second make it a lot less useful than it could be?

It did not seem that exciting to me. In particular, we've already found
out that \watch with zero delay is a pretty bad idea, so you'd have to
make a case for what smaller minimum to use if it's not to be 1 second.

regards, tom lane

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