adql: prefixes in TAP_SCHEMA.columns

[Patrick Dowler]

On 24/06/14 01:21 AM, Markus Demleitner wrote:
> So -- does anyone want to champion the adql: prefixes at this point?
> In particular, Pat, do you keep up your preference in favour of them?
> If nobody steps in, I'd remove them from the RegTAP PR before
> submitting it (tomorrow, probably), and I'd propose a clarification
> to the TAP specification in the Implementation Notes some time later.

The scenario I used a different prefix was when I had a column with an 
array (long[] or double[]). Without the prefix, this is still correctly 
described in the tap_schema with the size column, eg:

datatype: DOUBLE
size: 2

As long as clients are careful to look at the size in the tap_schema for 
datatype other than char or varchar, there is no ambiguity. Given the 
suggestion to allow non-standard types I think it is safe to say that 
non-standard size as we are using is also acceptable.

Given that, the prefix does not provide anything useful and I agree that 
we should probably drop them.


Obviously, clients already see both of these uses in the wild.. Should 
TAP services work to stop using the prefix now or with TAP-1.1?

Also, if we intend to allow non-standard datatype names, does that imply 
that we can stick them in the xtype attribute? I use and want to 
describe things like URIs, URLs, and UUIDs...


-- 

Patrick Dowler
Canadian Astronomy Data Centre
National Research Council Canada
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Victoria, BC V9E 2E7

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