The rdflib-postgresql from rdflib

rdflib-postgresql's Introduction

NOTE - this code is not maintained, and not guaranteed to work with newer versions of rdflib!

For RDBMS based persistence for RDFLib we recommend you use

https://github.com/RDFLib/rdflib-sqlalchemy

PostgreSQL :: a formula-aware RDFLib Store based on AbstractSQLStore

PostgreSQL RDFLib Store, formula-aware implementation. It stores its triples in the following partitions (per AbstractSQLStore):

Asserted non rdf:type statements
Asserted rdf:type statements (in a table which models Class membership). The motivation for this partition is primarily query speed and scalability as most graphs will always have more rdf:type statements than others
All Quoted statements

In addition it persists namespace mappings in a separate table

Requires RDFLib 3.

Install with:

$ pip install rdflib_postgresql

Basic usage:

>>> from rdflib import Graph, URIRef
>>> configString = "user=postgresql dbname=rdflibpostgresql_test"
>>> g = Graph('PostgreSQL', identifier=URIRef("http://example.com/g43"))
>>> g.open(configString, create=True)
1
>>> print(g)
<http://example.com/g43> a rdfg:Graph;rdflib:storage 
                    [a rdflib:Store;rdfs:label 'PostgreSQL'].
>>> print(g.store)
<Parititioned PostgreSQL N3 Store>
>>> print(g.identifier)
http://example.com/g43
>>> g.close()
>>>

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rdflib-postgresql's Issues

len miscounts statements in multiple contexts.

Test that reveals the bug.

    def testLenInMultipleContexts(self):
        oldLen = len(self.graph)
        self.addStuffInMultipleContexts()

        # addStuffInMultipleContexts is adding the same triple to
        # three different contexts. So it's only + 1
        self.assertEquals(len(self.graph), oldLen + 1)
        graph = Graph(self.graph.store, self.c1)
        self.assertEquals(len(graph), oldLen + 1)