OPG4Py Pgql¶

Python API for the PGQL-on-RDBMS client

class opg4py.pgql.PgqlConnection(java_pgql_connection)¶

Bases: object

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

class opg4py.pgql.PgqlPreparedStatement(java_pgql_prepared_statement)¶

Bases: opg4py.pgql._pgql_statement.PgqlStatement

Wrapper class for oracle.pg.rdbms.pgql.PgqlPreparedStatement

execute(parallel=0, dynamic_sampling=2, match_options=None, options=None)¶

Executes a PGQL Query, Modify or Create/Drop operation on this instance’s property graph.

Supported query options (matchOptions) are the same as those for executeQuery.

Supported modify options are:

STREAMING=T Use result sets instead of temporary tables to perform the update.

AUTO_COMMIT=F Do not commit after performing the modify operation.

DELETE_CASCADE=F Do not delete incoming/outgoing edges when deleting a vertex.

Parameters

parallel – the degree of parallelism to use for query and update execution
dynamic_sampling – the value for dynamic sampling
match_options – additional options used to influence query translation and execution
options – additional options used to influence modify translation and execution

Returns

True if the provided PGQL query is a select, false for other statements

Throws:: PgqlToSqlException - if a server-side error occurs during translation or SQL execution oracle.pgql.lang.PgqlException - if a server-side error occurs or this method is called on a closed Statement

execute_query(timeout=0, parallel=0, dynamic_sampling=2, max_results=- 1, options=None)¶

Translates this instance’s PGQL statement into a SQL statement and executes the SQL against this instance’s property graph.

Supported query options are:

USE_RW=F Use CONNECT BY instead of recursive WITH for unbounded path traversals.

MAX_PATH_LEN=n Traverse at most n hops when evaluating unbounded path traversals.

EDGE_SET_PARTIAL=T Fetch properties for each start and end vertex found when reading edges from the query result.

Parameters

timeout – the number of seconds for query execution to finish
parallel – the degree of parallelism to use for query execution
dynamic_sampling – the value for dynamic sampling
max_results – the maximum number of rows returned
options – additional options used to influence query translation and execution

Returns

a PgqlResultSet object with the result of the provided PGQL query

Throws:: PgqlToSqlException - if a server-side error occurs during translation or SQL execution oracle.pgql.lang.PgqlException - if a server-side error occurs or this method is called on a closed Statement

set_array(param_index, value)¶

Sets the designated parameter to the given Java List value.

Parameters: param_index – the first parameter is 1, the second is 2, …
Param: value: the parameter value

set_boolean(param_index, value)¶

Sets the designated parameter to the given Java boolean value.

Parameters: param_index – the first parameter is 1, the second is 2, …
Param: value: the parameter value

set_double(param_index, value)¶

Sets the designated parameter to the given Java double value.

Parameters: param_index – the first parameter is 1, the second is 2, …
Param: value: the parameter value

set_float(param_index, value)¶

Sets the designated parameter to the given Java float value.

Parameters: param_index – the first parameter is 1, the second is 2, …
Param: value: the parameter value

set_int(param_index, value)¶

Sets the designated parameter to the given Java int value.

Parameters: param_index – the first parameter is 1, the second is 2, …
Param: value: the parameter value

set_long(param_index, value)¶

Sets the designated parameter to the given Java long value.

Parameters: param_index – the first parameter is 1, the second is 2, …
Param: value: the parameter value

set_string(param_index, value)¶

Sets the designated parameter to the given Java String value.

Parameters: param_index – the first parameter is 1, the second is 2, …
Param: value: the parameter value

set_timestamp(param_index, value)¶

Sets the designated parameter to the given Java Timestamp value.

Timestamp values are assumed to be in Coordinated Universal Time (UTC).

Parameters: param_index – the first parameter is 1, the second is 2, …
Param: value: the parameter value

class opg4py.pgql.PgqlResultSet(java_pgql_result_set)¶

Bases: object

Wrapper class for oracle.pg.rdbms.pgql.PgqlResultSet

absolute(row)¶

Move the cursor to the given row number in this ResultSet object.

If the row number is positive, the cursor moves to the given row number with respect to the beginning of the result set. The first row is 1, so absolute(1) moves the cursor to the first row.

If the row number is negative, the cursor moves to the given row number with respect to the end of the result set. So absolute(-1) moves the cursor to the last row.

Parameters: row – Row to move to
Returns: True if the cursor is moved to a position in the ResultSet object; False if the cursor is moved before the first or after the last row

after_last()¶: Place the cursor after the last row

before_first()¶: Set the cursor before the first row

close()¶: Free resources on the server taken up by this result_set object.

first()¶

Move the cursor to the first row in the result set

Returns: True if the cursor points to a valid row; False if the result set does not have any results

get(element)¶

Get the value of the designated element by element index or name

Parameters: element – Integer or string representing index or name
Returns: Content of cell

get_boolean(element)¶

Get the value of the designated element by element index or name as a Boolean

Parameters: element – Integer or String representing index or name
Returns: Boolean

get_date(element)¶

Get the value of the designated element by element index or name as a datetime Date

Parameters: element – Integer or String representing index or name
Returns: datetime.date

get_float(element)¶

Get the value of the designated element by element index or name as a Float

Parameters: element – Integer or String representing index or name
Returns: Float

get_integer(element)¶

Get the value of the designated element by element index or name as an Integer

Parameters: element – Integer or String representing index or name
Returns: Integer

get_list(element)¶

Get the value of the designated element by element index or name as a List

Parameters: element – Integer or String representing index or name
Returns: List

get_string(element)¶

Get the value of the designated element by element index or name as a String

Parameters: element – Integer or String representing index or name
Returns: String

get_time(element)¶

Get the value of the designated element by element index or name as a datetime Time

Parameters: element – Integer or String representing index or name
Returns: datetime.time

get_time_with_timezone(element)¶

Get the value of the designated element by element index or name as a datetime Time that includes timezone

Parameters: element – Integer or String representing index or name
Returns: datetime.time

get_timestamp(element)¶

Get the value of the designated element by element index or name as a Datetime

Parameters: element – Integer or String representing index or name
Returns: datetime.datetime

get_timestamp_with_timezone(element)¶

Get the value of the designated element by element index or name as a Datetime that includes timezone

Parameters: element – Integer or String representing index or name
Returns: datetime.datetime

get_value_type(element)¶

Get the type of value of the designated element by element index or name as an Integer

Parameters: element – Integer or String representing index or name
Returns: Integer

get_vertex_labels(element)¶

Get the value of the designated element by element index or name as a list of labels

Parameters: element – Integer or String representing index or name
Returns: list

last()¶

Move the cursor to the last row in the result set

Returns: True if the cursor points to a valid row; False if the result set does not have any results

next()¶

Move the cursor forward one row from its current position

Returns: True if the cursor points to a valid row; False if the new cursor is positioned after the last row

previous()¶

Move the cursor to the previous row from its current position

Returns: True if the cursor points to a valid row; False if the new cursor is positioned before the first row

print(file=None, num_results=1000, start=0)¶

Print the result set.

Parameters

file – File to which results are printed (default is sys.stdout)
num_results – Number of results to be printed
start – Index of the first result to be printed

relative(rows)¶

Move the cursor a relative number of row with respect to the current position. A negative number will move the cursor backwards.

Note: Calling relative(1) is equal to next() and relative(-1) is equal to previous. Calling relative(0) is possible when the cursor is positioned at a row, not when it is positioned before the first or after the last row. However, relative(0) will not update the position of the cursor.

Parameters: rows – Relative number of rows to move from current position
Returns: True if the cursor is moved to a position in the ResultSet object; False if the cursor is moved before the first or after the last row

class opg4py.pgql.PgqlSqlQueryTrans(java_pgql_sql_query_trans)¶

Bases: opg4py.pgql._pgql_sql_trans.PgqlSqlTrans

Wrapper class for oracle.pg.rdbms.pgql.PgqlSqlQueryTrans

get_return_types()¶

Get an array of column descriptors for the result columns in the query result.

Returns: result column descriptions

get_sql_bv_list()¶

Get a list of Bind Values to be used with this SQL translation. The first element in the list should set at position 1 in a JDBC PreparedStatement created from this SQL translation.

Returns: the list of bind values for this query translation

get_sql_translation()¶

Get the SQL string for the PGQL to SQL translation.

Returns: the SQL query string

class opg4py.pgql.PgqlSqlTrans(java_pgql_sql_trans)¶

Bases: object

Wrapper class for oracle.pg.rdbms.pgql.PgqlSqlTrans

get_translation_type()¶

Get the type for the PGQL to SQL translation.

Returns: a PgqlSqlTrans.TranslationType object with the SQL translation type

class opg4py.pgql.PgqlStatement(java_pgql_statement)¶

Bases: object

Wrapper class for oracle.pg.rdbms.pgql.PgqlStatement

cancel()¶

Allows to cancel currently running execute operation. Note that cancel does not rollback already executed modifications.

Throws: oracle.pgql.lang.PgqlException - When an error occurs while canceling current operation.

close()¶

Releases this PgqlStatment’s database and JDBC resources.

Closing this PgqlStatement will close all PgqlResultSets that were created from it.

Throws: oracle.pgql.lang.PgqlException

execute(pgql, parallel=0, dynamic_sampling=2, match_options=None, options=None)¶

Executes a PGQL Query, Modify or Create/Drop operation on this instance’s property graph.

Supported query options (matchOptions) are the same as those for executeQuery.

Supported modify options are:

STREAMING=T Use result sets instead of temporary tables to perform the update.

AUTO_COMMIT=F Do not commit after performing the modify operation.

DELETE_CASCADE=F Do not delete incoming/outgoing edges when deleting a vertex.

Parameters

pgql – the PGQL modify to execute
parallel – the degree of parallelism to use for query and update execution
dynamic_sampling – the value for dynamic sampling
match_options – additional options used to influence query translation and execution
options – additional options used to influence modify translation and execution

Returns

True if the provided PGQL query is a select, false for other statements

Throws:: PgqlToSqlException - if a server-side error occurs during translation or SQL execution oracle.pgql.lang.PgqlException - if a server-side error occurs or this method is called on a closed Statement

execute_query(pgql, timeout=0, parallel=0, dynamic_sampling=2, max_results=- 1, options=None)¶

Translates this instance’s PGQL statement into a SQL statement and executes the SQL against this instance’s property graph.

Supported query options are:

USE_RW=F Use CONNECT BY instead of recursive WITH for unbounded path traversals.

MAX_PATH_LEN=n Traverse at most n hops when evaluating unbounded path traversals.

EDGE_SET_PARTIAL=T Fetch properties for each start and end vertex found when reading edges from the query result.

Parameters

pgql – the PGQL query to execute
timeout – the number of seconds for query execution to finish
parallel – the degree of parallelism to use for query execution
dynamic_sampling – the value for dynamic sampling
max_results – the maximum number of rows returned
options – additional options used to influence query translation and execution

Returns

a PgqlResultSet object with the result of the provided PGQL query

Throws:: PgqlToSqlException - if a server-side error occurs during translation or SQL execution oracle.pgql.lang.PgqlException - if a server-side error occurs or this method is called on a closed Statement

get_batch_size()¶: Get the number of commands that should be batched when executing updates :return: the update batch size

get_fetch_size()¶: Get the the number of rows that should be fetched from the database when more rows are needed for a query result. :return: the query fetch size

get_modify_count()¶: Get the number of rows that were modified by last execute operation :return: The number of rows modified

get_result_set()¶

Retrieve the current result as a PgqlResultSet object.

This method should be called only once per result.

Returns: Current result as a ResultSet object or null if the query is not a SELECT query

set_batch_size(batch_size)¶: Set the number of commands that should be batched when executing updates :param batch_size: the update batch size

set_fetch_size(fetch_size)¶: Set the the number of rows that should be fetched from the database when more rows are needed for a query result. :param fetch_size: the query fetch size

translate_query(pgql, parallel=0, dynamic_sampling=2, max_results=- 1, options=None)¶

Translates this instance’s PGQL statement into a SQL statement.

Supported query options are:

USE_RW=F Use CONNECT BY instead of recursive WITH for unbounded path traversals.

MAX_PATH_LEN=n Traverse at most n hops when evaluating unbounded path traversals.

EDGE_SET_PARTIAL=T Fetch properties for each start and end vertex found when reading edges from the query result.

Parameters

pgql – the PGQL query to translate
parallel – the degree of parallelism to use for query execution
dynamic_sampling – the value for dynamic sampling
max_results – the maximum number of rows returned
options – additional options used to influence query translation

Returns

a PgqlSqlTrans object with the SQL translation and column metadata for the provided PGQL query

Throws:: PgqlToSqlException - if a server-side error occurs during translation oracle.pgql.lang.PgqlException - if a server-side error occurs or this method is called on a closed Statement

translate_statement(pgql, parallel=0, dynamic_sampling=2, max_results=- 1, match_options=None, options=None)¶

Translates the given PGQL statement into a series of SQL statements.

Parameters

pgql – the PGQL statement to translate
parallel – the degree of parallelism to use for query execution
dynamic_sampling – the value for dynamic sampling
max_results – the maximum number of rows returned
match_options – additional options used to influence query translation and execution
options – additional options used to influence DDL/DML translation and execution

Returns

the SQL statements and metadata necessary to execute the provided SQL statement

Throws:: PgqlToSqlException - if a server-side error occurs during translation oracle.pgql.lang.PgqlException - if a server-side error occurs or this method is called on a closed Statement

opg4py.pgql.get_connection(usr, 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