On 22/07/13 09:23, Minto van der Sluis wrote:
Hi Andy,
See below
Regards,
Minto
Op 21-7-2013 19:06, Andy Seaborne schreef:
Minto,
Do you want a shared database across the cluster (3 tier architecture
style)? That's what SDB woulD give you.
Yes, using a separate DB layer which most probably should be clustered
itself. Preferred database is postgres. As far as I understand this
would not be a problem for SDB. But somehow I fear a preformance drop
when switching to SDB. Is this justified?
Yes.
Laying over SQL/JDBC and preserving SPARQL (specifically XSD value)
semantics means a lot of trips to the database for a single query unless
it is a single graph pattern or graph pattern and OPTIONAL (no FILTERS).
The only SQL-level engines left at scale these days put SPARQL inside
the SQL engine, not layered on top.
Fuseki does this for TDB. It can be used as a shared DB server. TDB
is just the database engine.
We/Epimorphics run replicated Fusek's as well but update is not
instantly consistent (we don't need that for our usage).
If the interface in Clerezza were the SPARQL protocol, then choice of
the backend database is a deployment choice.
Is there a Clerezza TcProvider that works straight on the SPARQL
protocol? Most I have seen (TDB and Sesame) use native API's. The
Virtuoso TcProvider mentioned by Reto almost seem to work like this, but
is dedicated to Virtuoso and uses the jdbc route sending SPARQL requests.
Is there a SPARQL protocol provider?
Currently I have no SPARQL protocol provider. I use the Clerezza
TcProvider specifically the TDB implementation.
Andy
