Re: list of extended statistics on psql

po 31. 8. 2020 v 18:32 odesílatel Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>
napsal:

> On Mon, Aug 31, 2020 at 12:18:09PM -0400, Alvaro Herrera wrote:
> >On 2020-Aug-31, Tomas Vondra wrote:
> >
> >> I wonder if trying to list info about all stats from the statistics
> >> object in a single line is necessary. Maybe we should split the info
> >> into one line per statistics, so for example
> >>
> >> CREATE STATISTICS s (mcv, ndistinct, dependencies) ON ...
> >>
> >> would result in three lines in the \dX output. The statistics name would
> >> identify which lines belong together, but other than that the pieces are
> >> mostly independent.
> >
> >Yeah, that's what I'm suggesting. I don't think we need to repeat the
> >name/definition for each line though.
> >
> >It might be useful to know how does pspg show a single entry that's
> >split in three lines, though.
> >
>
> Ah, I didn't realize you're proposing that - I assumed it's broken
> simply to make it readable, or something like that. I think the lines
> are mostly independent, so I'd suggest to include the name of the object
> on each line. The question is whether this independence will remain true
> in the future - for example histograms would be built only on data not
> represented by the MCV list, so there's a close dependency there.
>
> Not sure about pspg, and I'm not sure it matters too much.
>

pspg almost ignores multiline rows - the horizontal cursor is one row every
time. There is only one use case where pspg detects multiline rows - sorts,
and pspg ensures correct content for multiline rows displayed in different
(than input) order.

Regards

Pavel

>
> regards
>
> --
> Tomas Vondra http://www.2ndQuadrant.com
> PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
>