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Re: Do we need DELETE and CLEAR?

From: Axel Polleres <axel.polleres@deri.org>
Date: Thu, 25 Mar 2010 10:44:46 +0000
Cc: "Andy Seaborne" <andy.seaborne@talis.com>, <public-rdf-dawg@w3.org>
Message-Id: <B3ABC707-BB9A-4683-8023-6948D0DD2BE0@deri.org>
To: Steve Harris <steve.harris@garlik.com>
small side comment:

 DELETE DEFAULT

... the keyword DEFAULT is a bit confusing, since I see the update spec now speak about both an "unnamed" and a 
"default" graph at various places... I suppose these are the same, so terminology used for the graph store 
should be unified, probably.

Axel

On 11 Mar 2010, at 12:02, Steve Harris wrote:

> On 11 Mar 2010, at 10:34, Andy Seaborne wrote:
> 
> > It's not been a support issue with the released update language 
> > documented in the submission.
> >
> > Style-wise, verb-rich does not worry me.  The verbs should have a 
> > logical categorization, separating deleting triples and managing 
> > graphs say.
> >
> > In one design, theer was "REMOVE" for "DELETE DATA" - that did not 
> > receive much enthusiasm.
> >
> > On 11/03/2010 08:29, Steve Harris wrote:
> >> Observation about SPARQL Update syntax:
> >>
> >> SPARQL Update is quite verb-rich, making it (IMHO) harder to learn 
> >> the
> >> syntax, and it seems to me that one of CLEAR and DELETE is 
> >> redundant now:
> >>
> >> DELETE GRAPH <a>
> >> DELETE DEFAULT # see previous mail
> >
> > I find that confusing usage - is that CLEAR or DROP?
> 
> DELETE as in SQL, so CLEAR in SPARUL. DROP is distinct in both.
> 
> I don't really see how
>    DELETE WHERE { GRAPH <a> { ?x ?y ?z } }
> could be clear, but
>    DELETE GRAPH <a>
> not be, but could be just me.
> 
> c.f. DELETE FROM a ; DELETE FROM a WHERE 1 ; DROP a ; in SQL
> 
> > You explain below it's CLEAR but reading it in natural language, I 
> > would have gone for a reading of get rid of the GRAPH (i.e. DROP).
> 
> OK, but anyone more familiar with SQL than SPARUL would understand I 
> think.
> 
> > It is useful to have an explicit "delete everything" operation 
> > (rather than say "DELETE WHERE { ?s ?p ?o }" both for simple 
> > implementations and also the application writer because it's quite a 
> > major thing to do.
> 
> Sure, I wasn't arguing against the sugar, just against giving the 
> sugar it's own verb.
> 
> > CLEAR is an abbreviation of the abbreviated syntax (half :-).
> 
> Indeed :)
> 
> > c.f. SQL TRUNCATE.
> >
> > Identifying the DEFAULT graph seems an interesting thing to do.
> 
> That's for reasons of clarity, and (non-technical) ambiguity. See 
> other mail.
> 
> - Steve
> 
> --
> Steve Harris, Garlik Limited
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Received on Thursday, 25 March 2010 10:45:21 GMT

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