1. 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

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

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)

Creates a new PgqlPreparedStatement object, which represents a pre-compiled PGQL statement.

Parameters: pgql – the PGQL query to compile
Returns: a new 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_schema(schema)

Sets the schema name that will be used to execute PGQL queries with this connection.

Parameters: schema – the name of the schema