pycottas is a library for working with compressed RDF files in the COTTAS format. COTTAS stores triples as a triple table in Apache Parquet. It is built on top of DuckDB and provides an HDT-like interface.
- Compression and decompression of RDF files.
- Querying COTTAS files with triple patterns.
- RDFLib store backend for querying COTTAS files with SPARQL.
- Supports RDF datasets (quads).
- Can be used as a library or via command line.
PyPI is the fastest way to install pycottas:
pip install pycottasWe recommend to use virtual environments to install pycottas.
import pycottas
from rdflib import Graph, URIRef
pycottas.rdf2cottas('my_file.ttl', 'my_file.cottas', index='spo')
res = pycottas.search('my_file.cottas', '?s <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> ?o')
print(res)
pycottas.cottas2rdf('my_file.cottas', 'my_file.nt')
# COTTASDocument class for querying with triple patterns
cottas_doc = pycottas.COTTASDocument('my_file.cottas')
# the triple pattern can be a string (below) or a tuple of RDFLib terms
res = cottas_doc.search('?s <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> ?o')
# COTTASStore class for querying with SPARQL
graph = Graph(store=pycottas.COTTASStore('my_file.cottas'))
res = graph.query('''
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
SELECT DISTINCT ?s ?o WHERE {
?s rdf:type ?o .
} LIMIT 10''')
for row in res:
print(row)To execute via command line check the docs. It is also possible to serve COTTAS files as an SPARQL endpoint with pycottas-endpoint.
This work has received funding from the PIONERA project (Enhancing interoperability in data spaces through artificial intelligence), a project funded in the context of the call for Technological Products and Services for Data Spaces of the Ministry for Digital Transformation and Public Administration within the framework of the PRTR funded by the European Union (NextGenerationEU)
pycottas is available under the Apache License 2.0.
Universidad Politécnica de Madrid.
If you used pycottas in your work, please cite the ISWC paper:
@inproceedings{arenas2026cottas,
title = {{COTTAS: Columnar Triple Table Storage for Efficient and Compressed RDF Management}},
author = {Arenas-Guerrero, Julián and Ferrada, Sebastián},
booktitle = {Proceedings of the 24th International Semantic Web Conference},
year = {2026},
publisher = {Springer Nature Switzerland},
isbn = {978-3-032-09530-5},
pages = {313--331},
doi = {10.1007/978-3-032-09530-5_18},
}