Hi Ivan,
thanks again for your fast response!
I suppose the position of the G(raph) in the index pattern shouldn't
matter, since the graph part is not position bound, or does it make a
difference to create a SPGO or SGPO index, for example?
Besides: in my application I only have one (i.e. the default) graph. Is
there a more optimal way to store this, e.g. a Triple structure, while
still making use of the existing functions, such as ttlp_mt(...)?
Best regards,
Thomas
Ivan Mikhailov schrieb:
Thomas,
Quads are stored in RDF_QUAD table, as follows:
create table DB.DBA.RDF_QUAD (
G IRI_ID,
S IRI_ID,
P IRI_ID,
O any,
primary key (G,S,P,O)
)
create bitmap index RDF_QUAD_OGPS on DB.DBA.RDF_QUAD (O, G, P, S)
;
(the very beginning of libsrc/Wi/sparql.sql if you build from sources.)
If you performs queries that does not specify fixed graph names, but
specify fixed predicates, the following indexes are quite useful:
create bitmap index RDF_QUAD_PSOG on DB.DBA.RDF_QUAD (P, S, O, G);
create bitmap index RDF_QUAD_POSG on DB.DBA.RDF_QUAD (P, O, S, G);
You can create other indexes as well. Bitmap indexes are preferable, but
if O is the last column then the index can not be bitmap, so it could
be, e.g.
create index RDF_QUAD_PSGO on DB.DBA.RDF_QUAD (P, S, G, O);
but not
create bitmap index RDF_QUAD_PSGO on DB.DBA.RDF_QUAD (P, S, G, O);
Best Regards,
Ivan Mikhailov,
OpenLink Software.
On Fri, 2008-02-22 at 15:46 +0100, Thomas Hornung wrote:
Hi,
are there any special indices that can be turned on for querying RDF
data, e.g. subject/object -> predicate? AFAI understand the
documentation there is the possibility to use full text indices for
literals in the object position ( as mentioned in
http://docs.openlinksw.com/virtuoso/rdfsparqlrulefulltext.html), but I
couldn't find information on where to tweak other indices.
Does somebody know, if "special" indices are supported or are all
indices generated as a default setting.
Best regards,
Thomas
--
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Dipl.-Inf. Thomas Hornung
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phone: +49 (761) 203-8128
fax: +49 (761) 203-8122
e-mail: hornu...@informatik.uni-freiburg.de
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