** VOQL working group session, IVOA Interop, Oct 16, 2003 **

P. Dowler presented constraint-based model for VOQL

W. O'Mullane presented ADQL & SkyNode spec.

Q. What about querying using UCDs instead of table/column meta-data?
- astronomers want to use UCDs
- UCDs do not map to a table.column unambiguously

Q. Units for constants in the query?
- SkyNode/metadata specifies those used by the service

Q. Who does the translation?
- syntax: service
- concepts (UCDs?): astronomers

[The whole UCDs in ADQL seemed unresolved.]

* User Functions

- these are optional (extensions to ADQL)
	examples: transformations, precession calculation for proper motions, etc
ACTION: someone will put together a list of useful functions and post to the twiki

PROPOSAL: add a "Functions" method to the SkyNode interface

* SkyNode WD

Q. Namespace vs. version number?
- could use both
- note: this is to be used by a service to see what schema version the
submitted ADQL is using

Q I-17: could be removed, data-type should be part of service metadata
- assuming this is the "Column" metadata, but it wasn't specified

Q I-14: some people want to know precision/format for display purposes
(significant digits)

Q I-20: definition of XMATCH missing; implementors need to know the
algorithm in full detail

* General SkyNode issues

- desirable to cost queries in a general fashion, possibly estimate
data size and latency?

Q. Can a query be cancelled?
- no, but this probably falls within the realm of asynch execution and
job control (i.e. for the future)

Q. Does SkyNode make Cone Search obsolete?
- still good for small/simple providers that do not have a RDBMS, which
is necesarry to implement SkyNode

* looks like the Registry WG will not consider ADQL, but it was
pointed out that both need the "coverage" kinds of queries...

* someone should monitor and report on the use of XQuery/XPath within
commercial database vendor products...

ACTION: ADQL and SkyNode WD should be separate documents.  Both go back
to the VOQL WD for revision.