modules/rdf/store.zzm

NAME

rdf/store - std/db-backed RDF quad store.

SYNOPSIS

  from rdf/store import RDFStore;
  from rdf/term import rdf_iri, rdf_literal, rdf_quad;

  let store := RDFStore.temp();
  store.install_schema();
  store.add_quad(rdf_quad(
      rdf_iri("http://example.com/s"),
      rdf_iri("http://example.com/p"),
      rdf_literal("value"),
  ));

  let quads := store.find(rdf_iri("http://example.com/s"));

DESCRIPTION

RDFStore stores RDF quads in relational tables managed through std/db. Terms are interned, quads are indexed for lookup, and all graph operations use RDF term identity rather than object identity. The schema must be installed before use.

EXPORTS

Classes

• RDFStore

  Construct with new RDFStore(dbh: dbh) for SQLite or with an explicit backend of sqlite, mysql, or postgresql. prefix controls the table name prefix and defaults to rdf_.

  • temp()

    Returns new RDFStore(dbh: DB.temp()).

  • install_schema()

    Creates the store tables and indexes if needed.

  • schema_version()

    Returns the installed schema version, or 0 if the schema is absent.

  • verify_schema(Boolean strict := true)

    Checks that required schema objects exist. Throws on failure when strict is true; otherwise returns false.

  • drop_schema()

    Drops the store tables for this prefix.

  • begin(), commit(), rollback()

    Transaction helpers delegated to the database handle.

  • with_transaction(Function todo)

    Runs todo inside a transaction, committing on success and rolling back on exception.

  • add_term(term)

    Interns an RDF term and returns its database id.

  • term_for_key(String key)

    Returns the RDF term previously interned for key, or null.

  • add_quad(RDFQuad quad), add_quads(Array quads)

    Adds one or more quads. Duplicate quads are ignored by the store schema.

  • add_quads_bulk(Array quads)

    Adds many quads inside a transaction.

  • remove_quad(RDFQuad quad), remove_quads(Array quads)

    Removes one or more exact quads.

  • remove_match(subject := null, predicate := null, object := null, graph := null)

    Removes quads matching the supplied RDF term pattern. null is a wildcard.

  • clear()

    Removes every quad.

  • clear_graph(graph := null)

    Removes quads in the supplied graph, or the default graph when omitted.

  • graph_names()

    Returns named graph terms present in the store.

  • graph_exists(graph := null)

    Returns whether the supplied graph has any quads.

  • copy_graph(source := null, target := null)

    Copies all quads from source to target.

  • add_graph(source := null, target := null)

    Adds quads from source into target without clearing target.

  • move_graph(source := null, target := null)

    Copies then clears source.

  • replace_graph(graph := null, Array quads := [])

    Clears graph and inserts the supplied quads into it.

  • merge_store(RDFStore other)

    Adds all quads from another store.

  • count_quads(), count_terms()

    Return store counts.

  • statistics()

    Returns a dictionary of store counts and graph information.

  • diagnostics()

    Returns schema and backend diagnostic information.

  • explain_find(subject := null, predicate := null, object := null, graph := null)

    Returns a description of the lookup path selected for a pattern.

  • explicit_find(subject := null, predicate := null, object := null, graph := null)

    Returns matching stored quads without entailment.

  • find(subject := null, predicate := null, object := null, graph := null)

    Returns matching quads. Subclasses may add inferred quads.

  • serialize(serializer := null)

    Serializes all quads in the store. Defaults to NQuadsSerializer when no serializer object is supplied.

  • serialize_to(Path path, serializer := null)

    Serializes all quads in the store to path. Defaults to NQuadsSerializer when no serializer object is supplied.

COPYRIGHT AND LICENCE

rdf/store is copyright Toby Inkster.

It is free software; you may redistribute it and/or modify it under the terms of either the Artistic License 1.0 or the GNU General Public License version 2.