resuming progress on TAP
dtody at nrao.edu
Mon Feb 9 21:37:13 PST 2009
On Tue, 10 Feb 2009, Keith Noddle wrote:
>> One way to approach this would be to follow the same strategy that the VOQL
>> group did when separating ADQL and TAP: we could specify the "DAL
>> parameter-based query language" in a separate document that goes through
>> the standards process. It would be usable (referenced) by all DAL services.
>> The TAP spec would refer to the ADQL spec as a required language and allow
>> for use of other languages.
>> Mechanically, the TAP service metadata would have to describe which query
>> languages and versions are supported, but we have to do that in any case.
> I agree. I like that it frees up the option to relatively easily add other
> optional querying capabilities (XQuery for object databases/other XML data
> resources, maybe?) at some point in the future.
The draft TAP spec already provides for alternate query languages:
the LANG parameter, which could be used to specify native SQL or maybe
XQuery - in general any syntax which behaves relationally and returns
a table result. Indeed this is a nice feature, but it has nothing
to do with provision of parameter based queries for table access,
which are optimized for typical astronomical use cases.
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