Obscore 1.1 Erratum 3: Drop obs_id non-NULL requirement

[Markus Demleitner]

Hi Pat,

On Tue, Apr 26, 2022 at 08:28:34AM -0700, Patrick Dowler wrote:
> In the very last sentence with advice for query writers, "obs_id is not
> null" will omit results which is likely not what people want. Instead, they
> just need to treat NULL obs_id as not equal to another NULL obs_id, which
> is normal database semantics for NULL values. Thus, NULL obs_id(s) always
> indicates distinct observations.

Fair enough.  I've changed the language to:

  If this erratum is accepted authors of queries inspecting obs_id
  are advised to not group observations with a NULL obs_id; NULL
  obs_ids always indicate distinct observations.

(where I'd be open to dropping the if clause in that statement).

This perhaps also addresses Mireilles question...

On Tue, Apr 26, 2022 at 07:54:27PM +0200, Mireille LOUYS wrote:
> What does it mean to fill obs_id with NULL?

...somewhat more clearly.

Still, I second her plea:

> May be archive designers , providers can clarify this ?

If you are running an obscore service or if you are running queries
against obscore tables, please have a look at the impact assessment
of https://wiki.ivoa.net/twiki/bin/view/IVOA/ObsCore-1_1-Erratum-3
and see if I've missed something.

Thanks,

          Markus