Re: controlling psql's use of the pager a bit more

From: Andres Freund <andres(at)2ndquadrant(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Andrew Dunstan <andrew(at)dunslane(dot)net>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: controlling psql's use of the pager a bit more
Date: 2014-11-13 16:14:47
Message-ID: 20141113161447.GC29112@alap3.anarazel.de
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On 2014-11-13 11:09:06 -0500, Tom Lane wrote:
> Andrew Dunstan <andrew(at)dunslane(dot)net> writes:
> > I often get annoyed because psql is a bit too aggressive when it decides
> > whether to put output through the pager, and the only way to avoid this
> > is to turn the pager off (in which case your next query might dump many
> > thousands of lines to the screen). I'd like a way to be able to specify
> > a minumum number of lines of output before psql would invoke the pager,
> > rather than just always using the terminal window size.
>
> Are you saying you'd want to set the threshold to *more* than the window
> height? Why?

Not sure what that'd be useful for.

What I've noticed more than once is that it'd be useful to force the
pager if the result is wider than the screen.

> My impression is that the problem is not with the threshold as such,
> it's that psql is not terribly careful about determining how many lines
> it will put out (ie, the value being compared to the threshold isn't
> 100% reliable). If that's correct, then a hand-set threshold isn't
> really going to make you happier, and what's needed is some hard work
> on improving the quality of the lines-to-be-output estimates.

If it's that, I've personally solved that problem for me by adding -F
(aka --quit-if-one-screen) to $LESS.

Greetings,

Andres Freund

--
Andres Freund http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services

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