Re: machine-readable explain output v4

On Tuesday 11 August 2009 21:59:48 Andrew Dunstan wrote:
> Tom Lane wrote:
> > Mike <ipso(at)snappymail(dot)ca> writes:
> >> Have any tool authors stepped up and committed resources to utilizing
> >> this feature in the near term?
> >
> > I don't think anyone's promised much. If you want to have a go at using
> > it, we'd be very happy.
> >
> >> I'm guessing that my vision likely exceeds the scope of this feature in
> >> its initial form at least, but assuming no one else has stepped up, I'm
> >> more than willing to start committing resources as early as this
> >> weekend with the understanding that this feature is still in
> >> development and likely will change several times before or if its
> >> finally committed for 8.5.
> >
> > It's definitely committed for 8.5, but the exact format of the output
> > is (obviously) still subject to change.
> Good. I had a look at this for a little while yesterday. I built it, did
> an install, loaded auto_explain and then ran the regression tests. I
> didn't like the output much. It looks like the XML has been dumbed down
> to fit a data model that works for JSON as well, particularly in the
> lack of use of attributes. An XML processor won't care that much, but
> humans will certainly find it more tiresome to read. In effect we are
> swapping horizontal expansion for vertical expansion. It would be nicer
> to be able to fit a plan into a screen.
The problem is that nobody yet came up with one that is easy to generate and
liked by many people...
Aesthetically I do not like the current schema as well, but personally I don't
think it matters that much.

Everything fancy has the problem of requiring relatively much code...

> I also took the last relaxng spec I could find and used a nice little
> tool called Trang to translate it into an XML Schema spec. The good news
> is that that worked. The bad news is that the spec almost certainly
> needs some tightening, especially around those elements that probably
> should be XML attributes.
Unrelated to the other issues the relaxng schema has some missing pieces if I
remember it correctly (constraint => constraint-name, trigger => trigger-name)
I think). It is also by far not strict enough yet...

Andres