2. Creating a PGQL-on-RDBMS statement¶

The following classes can be used to create PGQL statements and prepared statements accordingly.

class opg4py.pgql.PgqlStatement(java_pgql_statement)

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

class opg4py.pgql.PgqlPreparedStatement(java_pgql_prepared_statement)

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