Connecting using PGQL-on-RDBMS
To connect using DB credentials directly the following convenience method can be used, otherwise a JDBC connection object needs to be provided.
- pgql.get_connection(pwd, jdbc_url)
Get a DB connection.
- Parameters
usr – the DB user
pwd – the DB password
jdbc_url – the DB jdbc url
- Returns
A PgqlConnection
Connecting to PGQL-on-RDBMS involves getting a connection object, that allows further operations such as creating a statement or retrieving metadata on the underlying JDBC connection.
- class opg4py.pgql.PgqlConnection(java_pgql_connection)
Wrapper class for oracle.pg.rdbms.pgql.PgqlConnection.
- clear_graph_metadata_cache()
Clear the cache that stores graph metadata.
- clear_translation_cache()
Clear the cache that stores translations.
- close()
Free the resources of the internal JDBC connection.
- create_statement()
Creates a new PgqlStatement object, which is used to execute PGQL queries.
- Returns
a new PgqlStatement object that can be used to perform PGQL queries
- disable_graph_metadata_cache()
Disable the cache that stores graph metadata.
- disable_translation_cache()
Disable the cache that stores translations.
- enable_graph_metadata_cache()
Enable the cache that stores graph metadata.
- enable_translation_cache()
Enable the cache that stores translations.
- static get_connection(java_sql_connection)
Factory method to get PgqlConnection instance.
- Parameters
java_sql_connection – a JDBC connection
- Returns
a PgqlConnection instance
- get_graph()
Get the graph name on which PGQL queries will be executed for this connection.
- Returns
the graph name for this connection
- get_jdbc_connection()
Get the JDBC connection that is used to execute PGQL queries.
- Returns
the connection
- get_schema()
Get the schema name that will be used to execute PGQL queries with this connection.
If the schema has not been set, the schema from JDBC connection is returned.
- Returns
the schema set for this connection
- Throws:
PgqlToSqlException - if a database access error occurs or this method is called on a closed connection
- prepare_statement(pgql, timeout=0, parallel=0, dynamicSampling=2, maxResults=-1, matchOptions=None, options=None)
Creates a new PgqlPreparedStatement object, which represents a pre-compiled PGQL statement.
- Parameters
pgql – the PGQL query to compile
timeout – the number of seconds for query execution to finish
parallel – the degree of parallelism to use for query and modify execution
dynamicSampling – the value for dynamic sampling
maxResults – the maximum number of rows returned
matchOptions – additional options used to influence query translation and execution
options – additional options used to influence modify translation and execution
- Returns
a PgqlPreparedStatement object that can be used to efficiently execute the same query multiple times
- set_graph(graph)
Sets the graph name on which PGQL queries will be executed for this connection.
- Parameters
graph – the name of the graph
- set_graph_metadata_cache_max_capacity(max_capacity)
Set max capacity value for the graph metadata cache
- Parameters
max_capacity – value for max capacity
- set_schema(schema)
Sets the schema name that will be used to execute PGQL queries with this connection.
- Parameters
schema – the name of the schema
- set_translation_cache_max_capacity(max_capacity)
Set max capacity value for the translation cache
- Parameters
max_capacity – value for max capacity