[TAP] data type for column metadata

[Roy Williams]

Ninety-nine percent of functionality at five percent of cost YES PLEASE. 
For example multicone is simple, inclusive, and rough -- then you do the 
thoughtful crossmatch at home.  I would like to echo that argument but 
for time.

If you make a query that involves astronomical epoch, the query engine 
doesn't need to get all the leap seconds right. You just widen the query 
by a couple of minutes, and when you get the results home, figure out 
the precision part of the timescales. That may involve reading a 
published paper to find out the metadata you need, because whoever 
filled in the registry form for the TAP service might have failed to 
define timescale metadata properly.

If you do a query involving dates, and discover that the timezones are 
wrong, then you can work around it, or you can find out the timezone the 
server is expecting, and do the query again.

It is impossible to be perfect. Let's spend out time on Common Use 
Cases, Robustness, and Helpful Error Reporting instead of trying to get 
computers to make subtle and complex judgement calls.

Just my $0.02
Roy

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California Institute of Technology
626 395 3670