Andy, This seems like a good approach but does not appear to be in the Jena code base, which I suppose is your comment about an approach to developing work.
Does it make sense to create git clones that contain the new work? Or perhaps branches? Do you have a suggestion or direction you would like to see this go? Claude On Fri, Oct 28, 2016 at 2:35 PM, Andy Seaborne <a...@apache.org> wrote: > Claude, > > These may help: > > I have been thinking about an interface that is more oriented to the > storage than the full DatasetGraph. > > StorageRDF breaks down all the operations into those on the default graph > and those on named graphs. For just a graph, simply ignore the named graph > operations. > > https://github.com/afs/AFS-Dev/blob/master/src/main/java/pro > jects/dsg2/storage/StorageRDF.java > > There is an adapter to the DatasetGraph hierarchy (which is needed for > SPARQL): > > https://github.com/afs/AFS-Dev/blob/master/src/main/java/pro > jects/dsg2/DatasetGraphStorage.java > > If you want to only use existing classes, DatasetGraphTriplesQuads is the > place to start - used by TIM and TDB - yuo can implement without needing > quads/named graphs. Again, simply ignore (throw > UnsupportedOperationException for the named graph calls). > > Going the graph route could lead to rework later on for any kind of > performance issues because find(S,P,O) is so narrow and precludes union > default graph except by brute force. DatasetGraph work with the SPARQL > execution engine. > > We still need to discuss how best to approach developing work - it should > not get sucked up by the release cycle. > > Andy > > > On 26/10/16 19:21, Claude Warren wrote: > >> My plan is to start with a Graph implementation. We expect to write 3 >> tables: SPO, POS, OPS (I think). Currently we don't have an easy way to >> handle find( ANY, ANY, ANY) so I suspect we will just start with >> permitting >> a column scan on Cassandra. >> >> I have not looked at DynamoDB but as I recall there are significant >> differences under the hood. >> >> I expect that we will move on to a custom model or query engine to get the >> best performance but that is not what we are planning for the first cut. >> >> I am still waiting for management approval to do this at work .... >> sometimes it takes longer to get the paperwork done than it does to design >> the thing. >> >> >> Claude >> >> On Mon, Oct 17, 2016 at 6:39 PM, Paul Houle <paul.ho...@ontology2.com> >> wrote: >> >> I like DynamoDB as a target for this sort of thing. There are many >>> tasks which are small-scale yet critical where it would otherwise be >>> hard to provide a distributed and reliable database. Put that together >>> with Lambda, which does the same for computation, and you are cooking >>> with gas. >>> >>> I wrote a 1-1 translation of DynamoDB documents to RDF that I use >>> throughout an application; the code is DynamoDB idiomatic in every way, >>> just the application reads and writes (a constrained set of) RDF >>> documents. >>> >>> Right now I dump the documents from the DynamoDB system into a triple >>> store when I want a panoptic view, but with a distributed graph like >>> that would mean being able to run SPARQL queries against DynamoDB >>> directly. >>> >>> There are many products in the same family as Cassandra and DynamoDB and >>> it would be good to think through the math so we can approach them all >>> in a similar way. >>> >>> -- >>> Paul Houle >>> paul.ho...@ontology2.com >>> >>> On Mon, Oct 17, 2016, at 12:31 PM, A. Soroka wrote: >>> >>>> Yep, >>>> >>>> http://iswc2011.semanticweb.org/fileadmin/iswc/Papers/ >>>> >>> Workshops/SSWS/Ladwig-et-all-SSWS2011.pdf >>> >>>> >>>> indicates that they are indexing by subject. As someone who has >>>> implemented LDP, that is definitely the approach that makes sense there. >>>> >>>> --- >>>> A. Soroka >>>> The University of Virginia Library >>>> >>>> On Oct 17, 2016, at 12:20 PM, Andy Seaborne <a...@apache.org> wrote: >>>>> >>>>> IIRC It stores CBDs indexed by subject so it is the "other" model to >>>>> >>>> Rya. Better for LDP (??). >>> >>>> >>>>> Andy >>>>> >>>>> On 17/10/16 15:41, A. Soroka wrote: >>>>> >>>>>> There's also: >>>>>> >>>>>> https://github.com/cumulusrdf/cumulusrdf >>>>>> >>>>>> in a similar vein (RDF over Cassandra). Not sure what kind of >>>>>> >>>>> particular uses it expects to support. >>> >>>> >>>>>> --- >>>>>> A. Soroka >>>>>> The University of Virginia Library >>>>>> >>>>>> On Oct 17, 2016, at 7:02 AM, Andy Seaborne <a...@apache.org> wrote: >>>>>>> >>>>>>> Hi Claude, >>>>>>> >>>>>>> There is certainly interest from me. >>>>>>> >>>>>>> What the best thing to do depends on various factors. By putting it >>>>>>> >>>>>> in extras I presume you mean it gets added to the release? That is >>> not the >>> only way forward. >>> >>>> >>>>>>> An important aspect of Apache is "Community over code" - will there >>>>>>> >>>>>> be a community around this code? Is that community the same, or >>> significant overlap, as the Jena community? >>> >>>> >>>>>>> There are various reasons for wanting RDF over a column store - >>>>>>> >>>>>> which use cases are the most important for this work? >>> >>>> >>>>>>> They lead to different ways of using Cassandra. For example, >>>>>>> >>>>>> Rya(incubating) uses Accumulo tables as indexes, and partial scans of >>> the >>> table is streaming. Other systems try to use the columns for properties, >>> possibly more useful for LDP style than SPARQL. >>> >>>> >>>>>>> Andy >>>>>>> >>>>>>> On 15/10/16 18:38, Claude Warren wrote: >>>>>>> >>>>>>>> Howdy, >>>>>>>> >>>>>>>> We have a project at work that is implementing Jena Graph on >>>>>>>> >>>>>>> Cassandra. I >>> >>>> am wondering if there is enough interest here to accept it as a >>>>>>>> contribution. I was thinking that it might fit in the Extras >>>>>>>> >>>>>>> category. >>> >>>> >>>>>>>> I can not promise release of the code yet as I have to present it >>>>>>>> >>>>>>> to our >>> >>>> internal Intellectual Property group first. >>>>>>>> >>>>>>>> Thoughts? >>>>>>>> >>>>>>>> Claude >>>>>>>> >>>>>>>> >>>>>> >>>> >>> >> >> >> -- I like: Like Like - The likeliest place on the web <http://like-like.xenei.com> LinkedIn: http://www.linkedin.com/in/claudewarren
