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

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@dunslane.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.

cheers

andrew