Arrays of geometries?

Dave Morris dave.morris at
Wed Sep 6 20:05:40 CEST 2017


In an earlier discussion Markus suggested using a language feature to 
indicate whether a service supported arrays.


I'd like to build on that and define two features within that URI to 
indicate support for numeric and geometric arrays.


This would enable services to declare support one or the other or both.

If this is a useful approach I'll add a section about it in the next 
draft of the ADQL specification.

-- Dave

On 2017-09-05 12:24, Markus Demleitner wrote:
> Dear DAL,
> While implementing DALI 1.1 with a view to TAP 1.1, one of my test
> cases lead to the encoding of a 2-array of points to a
> <FIELD datatype="float" arraysize="2x2" xtype="point"...>
> This made me realise that, as far as I can see, it's unclear what
> that means by DALI.  And it leads to the more fundamental question of
> whether xtype amends the datatype -- which would support such usage
> -- or whether it amends (datatype, arraysize) -- which probably would
> outlaw things like these.
> So:
> Is anyone strongly in favour of such usage?  Note that another,
> perhaps more common, use case is arrays of timestamps, which *could*
> play a role in certain time series serialisations?
> ...or is anyone strongly opposed to it?
> Either way, I think it's one of these corner cases where we should
> somehow agree upon a policy.  Should xtype+array be allowed?
> Forbidden?  Undefined at this point?
>           -- markus

More information about the dal mailing list