A leveldb-backed persistence plugin store for RDFLib

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An adaptation of RDFLib BerkeleyDB Store’s key-value approach, using LevelDB as a back-end.

Implemented by Gunnar Grimnes, based on an original contribution by Drew Perttula.

Migrated to Python 3 / RDFLib=>6 and adjusted to use the plyvel / plyvel-wheels Python-LevelDB inferface by Graham Higgins.

Installation options

Install with pip from github repos

pip install git+https://github.com/RDFLib/rdflib-leveldb#egg=rdflib_leveldb`

Install by cloning github repos, then pip install

git clone https://github.com/RDFLib/rdflib-leveldb.git
cd rdflib-leveldb
pip install .
# Optionally
pip install -r requirements.dev.txt
./run_tests.py

Install by cloning github repos, then python setup.py install

git clone https://github.com/RDFLib/rdflib-leveldb.git
cd rdflib-leveldb
python setup.py install
# Optionally
pip install -r requirements.dev.txt
./run_tests.py

Example usage:

from rdflib import plugin, Graph, URIRef
from rdflib.store import Store
import tempfile
import os


def example():
    path = os.path.join(tempfile.gettempdir(), "testleveldb")
    store = plugin.get("LevelDB", Store)(identifier=URIRef("rdflib_leveldb_test"))

    g = Graph(store)
    g.open(path, create=True)

    # Parse in an RDF file hosted on the Internet
    g.parse("http://www.w3.org/People/Berners-Lee/card")

    # Loop through each triple in the graph (subj, pred, obj)
    for subj, pred, obj in g:
        # Check if there is at least one triple in the Graph
        if (subj, pred, obj) not in g:
            raise Exception("It better be!")
    assert len(g) == 86, len(g)
    g.close()

    g.destroy(configuration=path)

A note on install dependencies as required/resolved by setup.py / pip:

Linux

The implementation of the rdflib-leveldb “LevelDB” Store depends on:

1. The C++ leveldb library
2. The Plyvel Python-to-leveldb interface.

The leveldb library is installed using the appropriate package manager.

sudo apt install leveldb-dev

Windows / MacOS

The implementation of the rdflib-leveldb “LevelDB” Store depends on a Python wheels package plyvel-wheels which includes platform-specific binaries for the leveldb library.

The task of installing a platform-specific Plyvel wrapper is handled with:

pip install -r requirements.txt (for standard use of this RDFLib Store)

or

pip install -r requirements.dev.txt (for module development)

or just

python setup.py install