W3C home > Mailing lists > Public > public-rdf-dawg@w3.org > January to March 2010

Re: Do we need DELETE and CLEAR?

From: Steve Harris <steve.harris@garlik.com>
Date: Thu, 11 Mar 2010 12:02:00 +0000
Cc: "public-rdf-dawg@w3.org Group" <public-rdf-dawg@w3.org>
Message-Id: <12442A72-C245-4298-8782-EEB633512741@garlik.com>
To: Andy Seaborne <andy.seaborne@talis.com>
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
2 Sheen Road, Richmond, TW9 1AE, UK
+44 20 8973 2465  http://www.garlik.com/
Registered in England and Wales 535 7233 VAT # 849 0517 11
Registered office: Thames House, Portsmouth Road, Esher, Surrey, KT10  
9AD
Received on Thursday, 11 March 2010 12:02:31 GMT

This archive was generated by hypermail 2.3.1 : Tuesday, 26 March 2013 16:15:41 GMT