> > | In my opinion, in an ideal world this would be something like a set of tags
(e.g., it's easy to imagine spectrum-image, or spectrum-timeseries, or
image-timeseries). A taxonomy of such classes (the
"tree") could then be used for query expansion by clients. However, there
are no set-valued columns in ADQL, and faking them using, e.g., strings and SQL
patterns ("=AND producttype like '%/spectrum/%'=") would defeat indexing and
simply be ugly. So, I'd say make a catalog, ideally using the
StandardKeyEnumeration from StandardsRegExt, and "other" is simply the SQL
NULL. Tell both data providers and consumers not to fill in the type if
there's not a good match. Ideally, the StandardKeyEnumeration would in
the descriptions try to cover as many real data products as possible
("This category covers objective prism exposures").
My feeling is that that's the Pareto-correct way of doing things,
actually covering probably around 98% of the actual queries rather than just
80%. -- MarkusDemleitner - 04 Mar 2011 |