1.4.13. Do you support additional metadata
for triples, such as time-stamps, security tags etc?
Since quads (triple plus graph) are stored in a regular SQL
table with special data types, changing the table layout to add a
column is possible. This column would not however be visible to
SPARQL without some extra tuning. For coarse grain provenance and
security information, we recommend doing this at the graph level,
where triples that belong together are tagged with the same
provenance or security are in the same graph. The graph can then
have the relevant metadata as its properties.
If tagging at the single triple level is needed, this will most
often not be needed for all triples. Hence altering the table for
all triples may not be the best choice. Making a special table that
has the graph, subject, predicate and object of the tagged triple
as a key and the tag data as a dependent part may be more
efficient. Also, this table could be more easily accessed from
Using the RDF reification vocabulary is not recommended as a
first choice but is possible without any alterations.
Alterations of this nature are possible but we recommend
contacting us for specifics. We can provide consultancy on the best
way to do this for each application. Altering the storage layout
without some extra support from us is not recommended.