- From: Steve Harris <steve.harris@garlik.com>
- Date: Thu, 27 Sep 2012 10:26:18 +0100
- To: Lee Feigenbaum <lee@thefigtrees.net>
- Cc: David Wood <david@3roundstones.com>, W3C RDF WG <public-rdf-wg@w3.org>
- Message-Id: <B9B08B6A-02E5-4B4A-9416-5A56BEDB91A9@garlik.com>
On 2012-09-26, at 17:41, Lee Feigenbaum wrote: > On 9/26/2012 12:09 PM, David Wood wrote: >> * Some designs for carrying for metadata >> >> PROPOSED: In our dataset syntax, we'll say that metadata goes in the default graph >> +0.5, especially if it can be aligned with SPARQL service descriptions. >> >> > > What do existing systems do when importing a TriG file that contains data in the "default" graph? The Anzo store has no default graph, and therefore either throws an error or throws away any information in a TriG "default graph". Similarly, all TriG exported from Anzo does not have a default graph unless it's the serialization of a SPARQL RDF dataset (which by definition does have a default graph, of course). > > I bring this up because I brought up a related thread on public-sparql-dev recently: > > http://lists.w3.org/Archives/Public/public-sparql-dev/2012JulSep/0025.html > > In that thread, I asked: > > """ > Do all quad stores / named graph stores include a default graph? If the store that you develop or use does have a default graph, does that graph also have a name (URI)? > """ > > The answers were: > > Anzo -- no default graph (except ones assembled on the fly for querying). > OWLIM -- has a default graph with no URI > RDF::Query -- has a default graph with no URI > 4store & 5store -- default graph is a view on existing graphs (& therefore, I assume, doesn't exist for purposes of storing data) -- uses a "special" named graph for writing default data > TDB -- can either have an actual default graph or just use the default graph as a view onto the other named graphs > > Additionally, there was input from 3 implementers (SteveH, GregW, and Chime) that if they could re-implement their systems they would not include a default/unnamed graph. > > All of which is to say, I think there's a fair amount of evidence that the "default" or unnamed graph is not consistently used, and perhaps not widely used. We need to support it for compatibility, but I think it's a mistake to specify that anything important be put in that graph. +∞ - Steve -- Steve Harris, CTO Garlik, a part of Experian +44 7854 417 874 http://www.garlik.com/ Registered in England and Wales 653331 VAT # 887 1335 93 80 Victoria Street, London, SW1E 5JL
Received on Thursday, 27 September 2012 09:26:49 UTC