sage.database.postgres_backends.postgres_catalog package

Submodules

sage.database.postgres_backends.postgres_catalog.connector module

class sage.database.postgres_backends.postgres_catalog.connector.CatalogPostgresConnector(table_name: str, dbname: str, user: str, password: str, host: str = '', port: int = 5432, fetch_size: int = 500)

Bases: sage.database.postgres_backends.connector.PostgresConnector

A CatalogPostgresConnector search for RDF triples in a PostgreSQL database.

Args:

  • table_name: Name of the SQL table containing RDF data.

  • dbname: the database name.

  • user: user name used to authenticate.

  • password: password used to authenticate.

  • host: database host address (defaults to UNIX socket if not provided).

  • port: connection port number (defaults to 5432 if not provided).

  • fetch_size: The number of SQL rows/RDF triples to fetch per batch (defaults to 500).

delete(subject: str, predicate: str, obj: str) → None

Delete a RDF triple from the RDF graph.

Args:

  • subject: Subject of the RDF triple.

  • predicate: Predicate of the RDF triple.

  • obj: Object of the RDF triple.

from_config() → sage.database.postgres_backends.connector.PostgresConnector

Build a CatalogPostgresConnector from a configuration object.

The configuration object must contains the following fields: ‘dbname’, ‘name’, ‘user’ and ‘password’. Optional fields are: ‘host’, ‘port’ and ‘fetch_size’.

insert(subject: str, predicate: str, obj: str) → None

Insert a RDF triple into the RDF graph.

Args:

  • subject: Subject of the RDF triple.

  • predicate: Predicate of the RDF triple.

  • obj: Object of the RDF triple.

search(subject: str, predicate: str, obj: str, last_read: Optional[str] = None, as_of: Optional[datetime.datetime] = None) → Tuple[sage.database.postgres_backends.postgres_catalog.iterator.PostgresIterator, int]

Get an iterator over all RDF triples matching a triple pattern.

Args:

  • subject: Subject of the triple pattern.

  • predicate: Predicate of the triple pattern.

  • object: Object of the triple pattern.

  • last_read: A RDF triple ID. When set, the search is resumed for this RDF triple.

  • as_of: A version timestamp. When set, perform all reads against a consistent snapshot represented by this timestamp.

Returns:

A tuple (iterator, cardinality), where iterator is a Python iterator over RDF triples matching the given triples pattern, and cardinality is the estimated cardinality of the triple pattern.

sage.database.postgres_backends.postgres_catalog.iterator module

class sage.database.postgres_backends.postgres_catalog.iterator.PostgresIterator(cursor, connection, start_query: str, start_params: List[str], pattern: Dict[str, str], fetch_size: int = 500)

Bases: sage.database.db_iterator.DBIterator

A PostgresIterator implements a DBIterator for a triple pattern evaluated using a Postgre database file

has_next() → bool

Return True if there is still results to read, and False otherwise

last_read() → str

Return the index ID of the last element read

next() → Optional[Dict[str, str]]

Return the next solution mapping or None if there are no more solutions

sage.database.postgres_backends.postgres_catalog.queries module

sage.database.postgres_backends.postgres_catalog.queries.get_catalog_insert_many_query()

Build a SQL query to insert a RDF term into a PostgreSQL dataset

sage.database.postgres_backends.postgres_catalog.queries.get_catalog_insert_query()

Build a SQL query to insert a RDF term into a PostgreSQL dataset

sage.database.postgres_backends.postgres_catalog.queries.get_delete_query(table_name)

Build a SQL query to delete a RDF triple form a PostgreSQL dataset

sage.database.postgres_backends.postgres_catalog.queries.get_extract_query()
sage.database.postgres_backends.postgres_catalog.queries.get_insert_many_query(table_name)

Build a SQL query to insert a RDF triple into a PostgreSQL dataset

sage.database.postgres_backends.postgres_catalog.queries.get_insert_query(table_name)

Build a SQL query to insert a RDF triple into a PostgreSQL dataset

sage.database.postgres_backends.postgres_catalog.queries.get_locate_query()
sage.database.postgres_backends.postgres_catalog.queries.get_resume_query(subj, pred, obj, last_read, table_name, symbol='>=')

Get a prepared SQL query which resumes scanning for a triple pattern and the parameters used to execute it.

sage.database.postgres_backends.postgres_catalog.queries.get_start_query(subj, pred, obj, table_name)

Get a prepared SQL query which starts scanning for a triple pattern and the parameters used to execute it.

Module contents