Advanced Column Statistics

[Markus Demleitner]

Dear VO community,

Since doing Registry searches using spatial, temporal, and spectral
constraints[1] is slowly becoming a reality with VODataService 1.2 in
RFC (still open for community comments:
https://wiki.ivoa.net/twiki/bin/view/IVOA/VODataServiceV12RFC), it is
now time to think about the next step for blind discovery: Advanced
column statistics.

The short version of the use case is: "Give me a catalogue of X
approximately complete to 15 mag in V".

Based on Grégory's ideas I have written a note on this, in a format
somewhere between brainstorming and a roadmap, which Giulia has just
put up on the document repository:

https://ivoa.net/documents/Notes/colstatnote/index.html

It would be great if you could have a look at the text with a view
at:

* from the Apps perspective: Does the proposed metadata make sense
  for you?  Is there additional low-hanging fruit we could pick with
  sensible extensions or alterations to the plan?

* from the Registry perspective: How will we make data like this
  available for discovery purposes?  Is vs:Stats a sane way to
  represent it?

* from the DAL perspective: What would extended metadata in
  VODataService mean for TAP_SCHEMA?

* for operators: Could you come up the the proposed metadata?  Would
  you?  I'd be happy to work with you to have a few more
  prototype implementations (beyond DaCHS, as discussed in the
  note).

* for everyone: Are there any elephants in the room that I've
  overlooked so far?

I'd suggest followup comments should go to Registry.  And I'm happy
to have something like a spontaneous breakout on this at the next
interop (I'm told we'll have gathertown for it...)

Thanks,

          Markus

[1] cf. https://ivoa.net/documents/Notes/Regstc/, which in some way
is part one of the new note.