Registry query language (RQL)

[Tony Linde]

Might as well get this discussion started on the list before we meet...

> I think the answer to point 3, " - what 'language' is used to 
> query a registry" is ADQL. 

I think this is debatable. ADQL is designed to serve as a query language for
astronomical data, most of it stored in structured files or databases. The
most common model for a dataset to be queried will be a single table with
lots of columns.

It is likely that all but the smallest and most specialised (and local)
registries will be deployed using some sort of rdbms but it will not be a
single table type of model. Given the number of repeating elements in the
model, any deployment is likely to use a hierarchical structure of tables.

In the future, when xml databases are more efficient and scalable, I would
expect registries (the structure for which will be laid down in the standard
schema associated with RM document) to make use of them.

RQL therefore ought to be structured for querying registries whose data is
stored according to the schema which will be derived from the combination of
RM 0.8, schema 0.8.1 and the discussions here and at the interop meeting.

I think there is a good case for RQL to be based on Xquery or Xpath, rather
than another SQL derivative, non?

Cheers,
Tony. 

> -----Original Message-----
> From: Robert Hanisch [mailto:rjhanisch at worldnet.att.net] 
> Sent: 15 September 2003 01:22
> To: Tony Linde; registry at ivoa.net
> Subject: Re: agenda for Strasbourg interop workshop
> ...