Re: very long record lines in expanded psql output

čt 5. 8. 2021 v 15:30 odesílatel Platon Pronko <platon7pronko(at)gmail(dot)com>
napsal:

> Hi!
>
> > a) with line cursor
>
> Tried in different configurations, seems that line cursor works fine.
>
> > b) format detection - I try to detect the header line - and I expect this
> > line has the most length of all lines. I use a line with the same length
> as
> > the column's type info (data, border).
>
> I looked at pspg source, and here's what I found (please correct me if
> some/all
> of my assumptions are wrong):
>
> 1. Input handling and format detection happens in table.c readfile().
>
> 2. There's some variables in DataDesc - maxx and maxbytes - that store the
> longest line seen so far. But they are re-updated on each new row, so the
> fact
> that header is shorter shouldn't affect them.
>
> 3. Expanded header detection is handled by is_expanded_header function. It
> has
> ei_minx and ei_maxx return pointers, but when it is used from readfile()
> these
> pointers are set to NULL in both cases - so header length is simply
> ignored.
>

The problem can be in translate_headline in bad desc->headline_size

> > Did you test the wrapped format? It is working
> >
> > \pset format wrapped
> > \x
> > select * from pg_class;
>
> There's no difference in outputs in wrapped format, so pspg behavior is
> also unaffected.
>
> By the way, it seems that pspg recommends setting \pset border 2 anyway,
> so in vast
> majority of cases there should be no possibility of difference at all -
> proposed patch
> doesn't change output for \pset border 2 (because there's no sane way of
> making it
> look okay in presence of long fields anyway).
>

Although pspg prefers border 2, it is working for all configurations now.

I think your proposal is not good, because it is breaking consistency and
if people want similar output, then they can use a wrapped format.

Regards

Pavel

>
> Best regards,
> Platon Pronko
>