RDFLib BerkeleyDB deletion problem.

bdb-test.py

from datetime import datetime
from rdflib import Dataset
from rdflib.plugins.stores import sparqlstore
import shutil

db_directory = "/tmp/bdb-test"
dataset = Dataset("BerkeleyDB")
dataset.open (db_directory, create=True)
if not isinstance (dataset, Dataset):
    print ("Failed to setup BerkeleyDB store.")

print (f"# Triples in the store: {len(dataset)}")
query_0 = """
PREFIX test: <http://test.nonexisting/>
PREFIX rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX xsd:  <http://www.w3.org/2001/XMLSchema#>

INSERT DATA {
  GRAPH <test://default> {
    <dataset:1> rdf:type test:Dataset .
    <dataset:1> test:title "Hello"^^xsd:string .
    <dataset:1> test:modified_date "2024-01-29T12:59:54Z"^^xsd:dateTime .
  }
}
"""

dataset.update (query_0)

print (f"Triples in the store: {len(dataset)}")

for row in dataset:
    print (f"Row: {row}")

def generate_query ():
    current_time = datetime.strftime (datetime.now(), "%Y-%m-%dT%H:%M:%SZ")
    query = f"""
PREFIX test: <http://test.nonexisting/>
PREFIX rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX xsd:  <http://www.w3.org/2001/XMLSchema#>

DELETE {{
  GRAPH <test://default> {{
    ?dataset test:title ?title .
    ?dataset test:modified_date ?modified_date .
  }}
}}
INSERT {{
  GRAPH <test://default> {{
    ?dataset test:title "Test"^^xsd:string .
    ?dataset test:modified_date "{current_time}"^^xsd:dateTime .
  }}
}}
WHERE {{
  GRAPH <test://default> {{
    ?dataset rdf:type test:Dataset .
    ?dataset test:title ?title .
    ?dataset test:modified_date ?modified_date .
  }}
}}
"""
    return query

query_1 = generate_query()
dataset.update (query_1)
print (f"Triples in the store: {len(dataset)}")

query_2 = generate_query()
dataset.update (query_2)
print (f"# Triples in the store: {len(dataset)}")

for row in dataset:
    print (f"Row: {row}")

dataset.close()
shutil.rmtree (db_directory)