HDT

A Rust library for the Header Dictionary Triples compressed RDF format, including:

• loading the HDT default format as created by hdt-cpp
• efficient querying by triple patterns
• serializing into other formats like RDF Turtle and N-Triples using the Sophia adapter

However it cannot:

• load other RDF formats
• load other HDT variants

For this functionality and acknowledgement of all the original authors, please look at the reference implementations in C++ and Java by the https://github.com/rdfhdt organisation.

It also cannot:

• swap data to disk
• modify the RDF graph in memory
• run SPARQL queries

If you need any of the those features, consider using a SPARQL endpoint instead.

Examples

[dependencies]
hdt = "0.0.12"

use hdt::Hdt;

let file = std::fs::File::open("example.hdt").expect("error opening file");
let hdt = Hdt::Rc<str>::new(std::io::BufReader::new(file)).expect("error loading HDT");
// query
let majors = hdt.triples_with_sp("http://dbpedia.org/resource/Leipzig", "http://dbpedia.org/ontology/major");
println!("{:?}", majors.collect::<Vec<_>>());

You can also use the Sophia adapter to load HDT files and reduce memory consumption of an existing application based on Sophia:

use hdt::{Hdt,HdtGraph};
use sophia::term::BoxTerm;
use sophia::graph::Graph;

let file = std::fs::File::open("dbpedia.hdt").expect("error opening file");
let hdt = Hdt::<std::rc::Rc<str>>::new(std::io::BufReader::new(file)).expect("error loading HDT");
let graph = HdtGraph::new(hdt);
let s = BoxTerm::new_iri_unchecked("http://dbpedia.org/resource/Leipzig");
let p = BoxTerm::new_iri_unchecked("http://dbpedia.org/ontology/major");
let majors = graph.triples_with_sp(&s,&p);

If you don't want to pull in the Sophia dependency, you can exclude the adapter:

[dependencies]
hdt = { version = "0.0.12", default-features = false }