Re: [HACKERS] psql: Activate pager only for height, not width

[Brendan Jurd]

On Tue, 30 May 2017 at 05:30 Christoph Berg  wrote:

> Oh interesting, I didn't know about pager_min_lines. That sounds
> useful as well. +1 on the analogous pager_min_cols option.
>

On closer inspection, I note that psql already has a 'columns' \pset
option, which does control the width for triggering the pager, but also
controls the width for wrapping and auto-expanded mode purposes.  So, I can
set 'columns' to get the pager behaviour that I want, but I also get
unwanted effects where I'd rather let the default (terminal width) apply.

So if we were to add a 'pager_min_cols', we'd have to decide how it
interacts with 'columns'.  For example, to determine whether to trigger the
pager, we look for 'pager_min_cols' first, and if that is not set, then
fall back to 'columns'.  For all other width purposes, 'columns' would
continue to apply as present.

However, my feeling is that this is becoming a bit too fiddly.  If
'columns' did not already exist then 'pager_min_cols' would make more
sense, but as it does already exist, my preference is to leave 'columns'
as-is, and go for a height-only option to 'pager' instead.

Thoughts?

Cheers,
BJ

Re: [HACKERS] psql: Activate pager only for height, not width

[Christoph Berg]

Re: Jeff Janes 2017-05-29 

Re: [HACKERS] psql: Activate pager only for height, not width

[Jeff Janes]

On Sun, May 28, 2017 at 10:09 PM, Brendan Jurd  wrote:

> Hello hackers,
>
> I am often frustrated by the default behaviour of the psql pager, which
> will activate a pager if the output is deemed to be "too wide" for the
> terminal, regardless of the number of lines output, and of the
> pager_min_lines setting.
>
> This behaviour is sometimes desirable, but in my use patterns it is more
> often the case that I want the pager to activate for output longer than
> terminal height, whereas for output a little wider than the terminal, I am
> happy for there to be some wrapping.  This is especially the case with "\d"
> output for tables, where, at 80 columns, very often the only wrapping is in
> the table borders and constraint/trigger definitions.
>
> Usually I turn the pager off completely, and only switch it on when I am
> about to execute something that will return many rows, but what I'd really
> like is some way to tell psql to activate the pager as normal for height,
> but to ignore width.  My first thought was an alternate mode to \pset pager
> -- to {'on' | 'off' | 'always'} we could add 'height'.
>
> Another option is to add the ability to specify the number of columns
> which psql considers "too wide", analogous to pager_min_lines.  I could
> then set pager_min_cols to something around 150 which would work nicely for
> my situation.
>
> I don't have strong opinions about how the options are constructed, as
> long as it is possible to obtain the behaviour.
>
> I would be happy to produce a patch, if this seems like an acceptable
> feature add.
>

I'd like a feature like this.  I often run into the problem where one or
two lines of an EXPLAIN plan are wide enough to wrap, which causes the
pager to kick in.  Then when I exit the pager, it clears the contents so I
can't see that plan vertically adjacent to the one I'm trying to compare it
to.  I'd rather have the pager kick in if greater than some settable number
of the lines are too wide, or if the wrapped lines would push the height
above the height limit.  If just one line is too wide, I'd rather just deal
with them being wrapped.

(You can configure the pager not to redraw the screen when exited, but I
want it to redraw the screen after looking at 10,000 rows, just not after
looking ten rows, one of which was 170 characters wide)

Cheers,

Jeff

[HACKERS] psql: Activate pager only for height, not width

[Brendan Jurd]

Hello hackers,

I am often frustrated by the default behaviour of the psql pager, which
will activate a pager if the output is deemed to be "too wide" for the
terminal, regardless of the number of lines output, and of the
pager_min_lines setting.

This behaviour is sometimes desirable, but in my use patterns it is more
often the case that I want the pager to activate for output longer than
terminal height, whereas for output a little wider than the terminal, I am
happy for there to be some wrapping.  This is especially the case with "\d"
output for tables, where, at 80 columns, very often the only wrapping is in
the table borders and constraint/trigger definitions.

Usually I turn the pager off completely, and only switch it on when I am
about to execute something that will return many rows, but what I'd really
like is some way to tell psql to activate the pager as normal for height,
but to ignore width.  My first thought was an alternate mode to \pset pager
-- to {'on' | 'off' | 'always'} we could add 'height'.

Another option is to add the ability to specify the number of columns which
psql considers "too wide", analogous to pager_min_lines.  I could then set
pager_min_cols to something around 150 which would work nicely for my
situation.

I don't have strong opinions about how the options are constructed, as long
as it is possible to obtain the behaviour.

I would be happy to produce a patch, if this seems like an acceptable
feature add.

Regards,
BJ