TAP RFC [MTIME]

[Patrick Dowler]

Now with my implementor hat on:

On Thursday 17 September 2009 09:32:31 Patrick Dowler wrote:
> Is it extraneous? Once PQL is defined, one could find this information by
> doing two requests: MAXREC=0&SELECT=ALL and MAXREC=0&SELECT=PRIMARY, for
> example.

although it technically works, this is pretty painful for something this 
simple; it also does nothing for a smart adql client application that is 
trying to help a user write queries for a service they are exploring. 

> So, the first question is: should we just remove it as extraneous (at least
> in 1.0)?
>
> If we keep it, as purely a categorisation hint from the service provider,
> what do we change the column name in TAP_SCHEMA.columns to?

I think this is simple metadata that allows a service to better describe the 
content. Smart applications will be able to use it in conjunction with any 
query language to build default queries the user can tweak later on. It helps 
solve the problem that real databases have a lot of columns that are needed 
for specific things but will likely overwhelm someone new to that site. 

Creating views are an option for the service provider, but then the namespace 
has more database objects and realtionships between them that the users have  
to understand. 

My vote is to keep the concept of primary column(s), but rename it so it is 
not a pain to implement. 

-- 

Patrick Dowler
Tel/Tél: (250) 363-0044
Canadian Astronomy Data Centre
National Research Council Canada
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Centre canadien de donnees astronomiques
Conseil national de recherches Canada
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