Configuring_Blazegraph
We’ve created some configuration files that represent various common “modes” with which you might want to run Blazegraph. You can find these and other modes in the form of properties files in the Blazegraph source tree, in the “bigdata-sails” module, at:
bigdata-sails/src/samples/com/bigdata/samples [1]
If none of those modes seem right for you, let us help you devise the mode that is right for your particular problem. We offer development support, production support, and custom services around the platform.
This turns on all of Blazegraph’s goodies - statement identifiers, free-text index, incremental inference and truth maintenance. The following is how you would use Blazegraph in a system that requires statement-level provenance, free-text search, and incremental load and retraction. File fullfeature.properties:
# As you can see, bigdata is nearly in full-feature mode by default.
# All we do here is turn on the provenance mode.
com.bigdata.rdf.store.AbstractTripleStore.statementIdentifiers=true
# RWStore (scalable single machine backend)
com.bigdata.journal.AbstractJournal.bufferMode=DiskRW
This mode turns off all inference and truth maintenance, for when you just need to store triples. File rdfonly.properties:
# changing the axiom model to none essentially disables all inference
com.bigdata.rdf.store.AbstractTripleStore.axiomsClass=com.bigdata.rdf.axioms.NoAxioms
# RWStore (scalable single machine backend)
com.bigdata.journal.AbstractJournal.bufferMode=DiskRW
We run Blazegraph in Fast Load Mode when we are evaluating load and query performance, for example with the LUBM harness. This turns off some features that are unnecessary for this type of evaluation (statement identifiers and the free text index), which increases throughput. This mode still does inference, but it is database-at-once instead of incremental. It also turns off the recording of justification chains, meaning it is an extremely inefficient mode if you need to retract statements (all inferences would have to be wiped and re-computed). This is a highly specialized mode for highly specialized problem sets.
[1] https://github.com/blazegraph/database/tree/master/bigdata-sails/src/samples/com/bigdata/samples
We've set up three modes for Blazegraph that configure the store properly for triples, triples with provenance, and quads. Look for the TRIPLES_MODE, TRIPLES_MODE_WITH_PROVENANCE, and QUADS_MODE on AbstractTripleStore.Options and BigdataSail.Options.
Currently Blazegraph does not support inference or provenance for quads, so those features are automatically turned off in QUADS_MODE.
