RE: [search-ws] Relationship of CQL to SPARQL/SQL?

["LeVan,Ralph" <levan@oclc.org>]

I don't have any wisdom to contribute on this.  CQL is about as far away
from SPARQL as it is from SQL.  They are completely different searching
paradigms.

On the other hand, CQL and the Lucene Query Language are reasonably
close.  I've not done any comprehensive analysis of the two, but I've
been able to write some simple translators from CQL to Lucene for my SRW
server.

Ralph

> -----Original Message-----
> From: Hammond, Tony [mailto:t.hammond@nature.com]
> Sent: Monday, January 25, 2010 12:15 PM
> To: OASIS SWS TC
> Subject: [search-ws] Relationship of CQL to SPARQL/SQL?
> 
> Hi:
> 
> One thing I wanted to bring up here was whether there should (or
could) be
> some kind of scoping note (either within the spec as an informational
annex)
> or somewhere else readily accessible (website?, paper?) that would
relate
> CQL to other well-known query initiatives - specifically SPARQL and
SQL.
> 
> This message (dated 2008-04-10, and cc'ed below for convenience) from
> MacKenzie Smith which quotes Rob Sanderson
> 
> https://simile.mit.edu/mail/ReadMsg?listName=Dev&msgId=25018
> 
> seems to provide a good starting point.
> 
> I, for one, could really do with some help in clarifying the role that
CQL
> has to play in searching bib records in a world that is now
increasingly
> atomizing to the datum level (cf. recent releases of data.gov.uk and
earlier
> data.gov) and is turning towards semantic solutions (SPARQL) as the ne
plus
> ultra having relied previously upon the relational model (SQL).
> 
> Are bib records really that different from data? Some kind of document
to
> set the context for the current work could be really helpful. Maybe
its just
> the level of granularity supported by bib apps that makes them
qualitatively
> different? And then besides bib vs data, there's also bib vs bib, e.g.
How
> does CQL stack up against Lucene/SOLR, etc?
> 
> Does that make any sense?
> 
> Cheers,
> 
> Tony
> 
> 
> ===
> Hi Kjetil,
> 
> I took the liberty of asking Rob Sanderson from the SRU technical
> committee about this,
> and here are his comments:
> 
> "The CQL <--> SPARQL Mapping question has come up (quite a while ago
now)
> and more commonly CQL <--> SQL.
> 
> The main challenge in any CQL <--> SPARQL mapping is the different
> things which the languages consider atomic.  SPARQL works at the rdf
> triple level, whereas CQL assumes that there is some record or item
> which contains information.  Normally you would want to model items as
a
> [named] graph of triples, so there's some discrepancy in what the
> queries should return.
> 
> In CQL <--> SQL it's a similar problem, in that the result of an SQL
> query is a table not zero or more items, but it's easier to turn a
table
> into XML than a set of RDF triples.
> 
> Secondly, CQL doesn't have the concept of variables, as there aren't
> relationships to follow.  So while in SPARQL you can do clever things
> like 'find all authors who have co-authored with someone who has
written
> a book that has "information" in the title', in CQL the context of
each
> sub-query isn't carried over to the rest of the query.
> 
> A mapping would at least require some definition of what an 'item' (or
> 'record') is from the matching graph. In the named graph world view
this
> is easier, as the trivial mapping would be record == named graph, but
in
> the all-triples-stand-alone view, it becomes rather arbitrary."
> 
> 
> Rob is happy to give this more thought if there's interest, and he can
> be found at
> [email hidden]
> 
> MacKenzie
> ===
> 
> 
>
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