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

From: Andrew Dunstan <andrew(at)dunslane(dot)net>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: controlling psql's use of the pager a bit more
Date: 2014-12-21 19:22:10
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On 11/15/2014 05:56 PM, Andrew Dunstan wrote:
> On 11/13/2014 11:41 AM, Andrew Dunstan wrote:
>> On 11/13/2014 11:09 AM, 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?
>> Because I might be quite happy with 100 or 200 lines I can just
>> scroll in my terminal's scroll buffer, but want to use the pager for
>> more than that. This is useful especially if I want to scroll back
>> and see the results from a query or two ago.
> This patch shows more or less what I had in mind.
> However, there is more work to do. As Tom noted upthread, psql's
> calculation of the number of lines is pretty bad. For example, if I do:
> \pset pager_min_lines 100
> select * from generate_series(1,50);
> the pager still gets invoked, which is unfortunate to say the least.
> So I'm going to take a peek at that.

The over-eager invocation of the pager due to double counting of lines
got fixed recently, so here's a slightly updated patch for a
pager_min_lines setting, including docco.



Attachment Content-Type Size
psqlminlines.patch text/x-patch 12.1 KB

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