semantica/docs/reference/triple_store.md

Triple Store Module

Store and query RDF triples with support for SPARQL queries and semantic reasoning using industry-standard triple stores.

Overview

• RDF Storage: Store subject-predicate-object triples
• SPARQL Queries: W3C-compliant query language
• Reasoning: RDFS and OWL reasoning
• Multiple Backends: RDFLib, Jena, Virtuoso, GraphDB
• Federation: Query across multiple triple stores

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Algorithms Used

Query Algorithms

• SPARQL Query Optimization: Join reordering with selectivity estimation
• Triple Pattern Matching: Index-based lookup with B+ trees
• Graph Pattern Matching: Subgraph isomorphism
• Query Planning: Cost-based optimization

Indexing

• SPO Index: Subject-Predicate-Object index
• POS Index: Predicate-Object-Subject index
• OSP Index: Object-Subject-Predicate index
• Six-Index Scheme: All permutations for optimal query performance

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Main Classes

TripleStore

Methods:

Method	Description	Algorithm
add_triple(subject, predicate, object)	Add single triple	Index insertion
add_triples(triples)	Batch add triples	Bulk index insertion
query(sparql_query)	Execute SPARQL query	Query optimization + execution
delete(pattern)	Delete matching triples	Pattern matching + deletion
serialize(format)	Serialize to RDF format	Format-specific serialization

Example:

from semantica.triple_store import TripleStore

store = TripleStore(backend="rdflib")

# Add triples
store.add_triple(
    subject="http://example.org/AppleInc",
    predicate="http://example.org/foundedBy",
    object="http://example.org/SteveJobs"
)

# SPARQL query
results = store.query("""
    SELECT ?company ?founder WHERE {
        ?company <http://example.org/foundedBy> ?founder .
    }
""")

for row in results:
    print(f"{row['company']} founded by {row['founder']}")

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SPARQLQueryEngine

Methods:

Method	Description	Algorithm
execute(query)	Execute SPARQL query	Parse + optimize + execute
parse_query(sparql)	Parse SPARQL syntax	SPARQL parser
optimize_query(query)	Optimize query plan	Join reordering
explain_query(query)	Explain query plan	Query plan visualization

SPARQL Query Types:

• SELECT: Retrieve variable bindings
• CONSTRUCT: Build RDF graph
• ASK: Boolean query
• DESCRIBE: Describe resources

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Configuration

# config.yaml - Triple Store Configuration

triple_store:
  backend: rdflib  # rdflib, jena, virtuoso, graphdb
  
  indexing:
    schemes: [SPO, POS, OSP]  # Index permutations
    
  query:
    optimize: true
    timeout: 30  # seconds

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See Also

• Knowledge Graph Module
• Ontology Module