(lots of questions - maybe if you gave some background, we can answer
better).
On 30/07/13 12:44, Rose Beck wrote:
Just like there was a paper for Jena SDB ("Efficient RDF Storage and
Retrieval in Jena2"), is there any paper for Jena TDB?
"Efficient RDF Storage and Retrieval in Jena2" is what we might call
"RDB", and is no longer part of the Jena project. SDB is a more
efficient (and different mapping) to SQL. It exists for enviroments
where using SQL is required. TDB scales better and executes faster.
On Tue, Jul 30, 2013 at 5:06 PM, Chris Dollin
<[email protected]>wrote:
On Tuesday, July 30, 2013 04:41:09 PM Rose Beck wrote:
Does Jena TDB support reification. If yes, then how?
Note that named graphs enable many of the uses of reification because a
graph can be treated as quoted. As statements often don't come in units
of one, named graph provide a way to handle groups of statements.
What are you trying to achieve?
What do you mean by "support reification"?
Also can you please give an example SPARQL query plan illustrating the
use
of reification in Jena.
There's nothing in SPARQL specific to reification. You just use the RDF
reification vocabulary.
And indeed the experience with the design was that there is a major
tradeoff of handling reification specially and performance. Just look
at the query in 5.1.
SPARQL is more complicated than RDQL. Proper handling can restrict the
amount of work sent to the database engine, requiring multiple JDBC
operations per SPARQL query.
That design loaded at maybe 1000 triples/s for the first 1m or so
triples : TDB loads at 30K for 100m, with bursts of 75+K in the first
million. TDB is same-process.
Andy
Chris
--
"It does not need to take events in their correct order."
/Hexwood/
Epimorphics Ltd, http://www.epimorphics.com
Registered address: Court Lodge, 105 High Street, Portishead, Bristol BS20
6PT
Epimorphics Ltd. is a limited company registered in England (number
7016688)
