HDT keeps big RDF datasets compressed while maintaining efficient search and browse operations.
To compile the library run make
under the directory hdt-lib
, this will generate the library and tools.
The implementation has the following dependencies:
- Serd This enables importing RDF data in the Turtle and N-Triples serialization formats specifically. The dependency is activated by default; to deactivate it, comment out the line
SERD_SUPPORT=true
in theMakefile
. - Raptor RDF Parser Library 2.x (optional) This enables importing RDF data in many serialization formats, e.g., RDF/XML, Turtle, N3, etc. The dependency is activated by default; to deactivate it, comment out the line
RAPTOR_SUPPORT=true
in theMakefile
. If Raptor or Serd is not used, the library will only be able to load RDF data in N-Triples format. - libz (optional) Enables loading N-Triples files compressed with GZIP (e.g.,
file.nt.gz
) and gzipped HDTs (file.hdt.gz
). The dependency is activated by default; to deactivate it, comment out the lineLIBZ_SUPPORT=true
in theMakefile
. - Kyoto Cabinet (optional) Enables generating big RDF datasets on machines without much RAM memory, by creating a temporary Kyoto Cabinet database. The dependency is deactivated by default; to activate it, uncomment the line
KYOTO_SUPPORT=true
in theMakefile
and edit the library include path (INCLUDES=
) as needed.
After building, these are the typical operations that you will perform: Create the HDT representation of your RDF data:
$ tools/rdf2hdt data/test.nt data/test.hdt
Convert an HDT to another RDF serialization format, such as N-Triples:
$ tools/hdt2rdf data/test.hdt data/test.hdtexport.nt
Open a terminal to search triple patterns within an HDT file:
$ tools/hdtSearch data/test.hdt
>> ? ? ?
http://example.org/uri3 http://example.org/predicate3 http://example.org/uri4
http://example.org/uri3 http://example.org/predicate3 http://example.org/uri5
http://example.org/uri4 http://example.org/predicate4 http://example.org/uri5
http://example.org/uri1 http://example.org/predicate1 "literal1"
http://example.org/uri1 http://example.org/predicate1 "literalA"
http://example.org/uri1 http://example.org/predicate1 "literalB"
http://example.org/uri1 http://example.org/predicate1 "literalC"
http://example.org/uri1 http://example.org/predicate2 http://example.org/uri3
http://example.org/uri1 http://example.org/predicate2 http://example.org/uriA3
http://example.org/uri2 http://example.org/predicate1 "literal1"
9 results shown.
>> http://example.org/uri3 ? ?
http://example.org/uri3 http://example.org/predicate3 http://example.org/uri4
http://example.org/uri3 http://example.org/predicate3 http://example.org/uri5
2 results shown.
>> exit
Extract the Header of an HDT file:
$ tools/hdtInfo data/test.hdt > header.nt
Replace the Header of an HDT file with a new one. For example, by editing the existing one as extracted using hdtInfo
:
$ tools/replaceHeader data/test.hdt data/testOutput.hdt newHeader.nt