[TAP] data type for column metadata

[Robert Hanisch]

I must have missed something.  In V0.31 table metadata could be returned in
an empty VOTable.  My recollection (now hazy) is that this is something
Francois was particularly interested in, and it seems to makes sense given
that the data can be returned in VOTables and the column metadata there is
what it is.

I think that a lot of queries could be written based on quite simple column
metadata.  We have seen this for years now in OpenSkyQuery.

Sorry if I missed a thread somewhere along the way.

Bob


On 4/1/09 12:20 PM, "Patrick Dowler" <patrick.dowler at nrc-cnrc.gc.ca> wrote:

> On 2009-03-31 23:08:05 Markus Demleitner wrote:
>> Again: What would be so bad with having clients request an empty VOTable
>> for the columns they are interested in to retrieve STC metadata?
> 
> We already came to the conclusion that VOTable datatypes do not fully capture
> what is needed to write queries, not to mention metadata aside from column
> descriptions. That is why we came up with the list of SQL types and once
> users have to get some metadata from VOSI or TAP_SCHEMA I don't think it is
> plausible to impose that they get the rest of it from the header of an empty
> VOTable.
> 
> Secondly, in the first example of  Section 5.1 in the doc you referred to
> (http://www.ivoa.net/Documents/Notes/VOTableSTC/VOTableSTC-20081018.html) they
> use one of the standard reference systems specified in STC-Lib:
> UTC-ICRS-TOPO. That is exactly what would be done here if we adopt the
> simpler compact form and a single metadata attribute (to specify something
> like UTC-ICRS-TOPO, for example).
> 
> my 2c,