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Re: SPARQL Update feature

From: Andy Seaborne <andy.seaborne@talis.com>
Date: Thu, 15 Jul 2010 20:44:03 +0100
Message-ID: <4C3F6503.7090004@talis.com>
To: Alexandre Passant <alexandre.passant@deri.org>
CC: Steve Harris <steve.harris@garlik.com>, SPARQL Working Group <public-rdf-dawg@w3.org>
Grammar updated:

[37]    Clear  	  	::=    	'CLEAR' 'SILENT'? GraphRefAll
[38]   	Drop 	  	::=   	'DROP' 'SILENT'? GraphRefAll
[39]   	Create 	  	::=   	'CREATE' 'SILENT'? GraphRef
[40]   	GraphRef 	::=   	'GRAPH' IRIref
[41]   	GraphRefAll 	::=   	GraphRef | 'DEFAULT' | 'NAMED' | 'ALL'

	Andy

On 15/07/2010 3:19 PM, Alexandre Passant wrote:
> Hi,
>
> On 13 Jul 2010, at 14:39, Andy Seaborne wrote:
>
>>
>>
>> On 13/07/2010 1:25 PM, Steve Harris wrote:
>>> On 2010-07-13, at 11:46, Alexandre Passant wrote:
>>>
>>> [ snip, all looks good to me ]
>>>
>>>> We initially thought that ALL includes also the default graph, but that will be a problem for removing all named graphs but not the default one (not sure that will happen so often, yet)
>>>> So better to have ALL = all named graphs, which leads to the following to clean the store
>>>>
>>>> DROP ALL
>>>> DROP DEFAULT
>>>>
>>>> or
>>>>
>>>> DROP ALL
>>>> CLEAR DEFAULT
>>>>
>>>> What do you think ?
>>>
>>> I prefer DROP/CLEAR ALL does everything, including the default graph. "ALL" implies that to me.
>>
>> I'm comfortable with that.
>>
>> Another possibility for completeness: a special form like
>>
>> RESET STORE
>>
>> that then puts it outside the issue of whether ALL is all named graphs or all graphs.
>
> Following the discussion on the last t-con on the ability to removed named graph (but not default) but also to remove all graphs, I suggest (as followed-up by Lee):
>
> DROP [ SILENT ] (GRAPH<uri>  | DEFAULT | NAMED | ALL)
>
> DROP DEFAULT : remove only default graph. It's dropped but implicitely re-created.
> DROP NAMED : remove all named graphs
> DROP ALL : remove all graphs (i.e. named graphs + default one) - RESET STORE could be an alias, but it introduces one more operation, which may not be useful in that case
>
> And use the same operations (including SILENT) for the CLEAR.
> As discussed previously, DROP DEFAULT == CLEAR DEFAULT (since default graph must exist, it's implicitly created after being DROPped), but I find more consistent to use same grammar for both.
>
> Alex.
>
>>
>>>
>>> If I really want to leave the named graph, and CLEAR the others I can do that with:
>>>
>>> DELETE WHERE { GRAPH ?g { ?x ?y ?z } }
>>>
>>> Admittedly there's no DROP equivalent, for graphs that don't do empty graph culling, but that's well into corner cases AFAIC.
>>
>> It's not a corner case for me - some implementations are quite happy with empty graphs and they don't naturally get culled.  Such grah stores are a collection of graphs, not stored in a common quad table.
>>
>>>
>>> Otherwise, you could add a "GRAPH *" like syntax, meaning all named graphs, but I predict that users would confuse GRAPH * and ALL a lot.
>>
>> Maybe - I'm more comfortable with DROP GRAPH *. With an explicit use of GRAPH, and DEFAULT (not GRAPH DEAFULT) it makes sense and is explainable.  At least "DROP GRAPH *" does not destroy data that the user didn't want addressed.
>>
>> 	Andy
>>
>>>
>>> - Steve
>>>
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>
> --
> Dr. Alexandre Passant
> Digital Enterprise Research Institute
> National University of Ireland, Galway
> :me owl:sameAs<http://apassant.net/alex>  .
>
>
>
>
>
>
Received on Thursday, 15 July 2010 19:44:30 GMT

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