Transaction API

Spanner read-write transaction support.

class google.cloud.spanner_v1.transaction.Transaction(session)

Implement read-write transaction semantics for a session.

Parameters

session (Session) – the session used to perform the commit
Raises

ValueError – if session has an existing transaction

_enter_()

Begin with block.

_exit_(exc_type, exc_val, exc_tb)

End with block.

batch_update(statements)

Perform a batch of DML statements via an ExecuteBatchDml request.

Parameters

statements (Sequence[Union[ *[str](https://python.readthedocs.io/en/latest/library/stdtypes.html#str), Tuple[[str](https://python.readthedocs.io/en/latest/library/stdtypes.html#str), Dict[[str](https://python.readthedocs.io/en/latest/library/stdtypes.html#str), Any], **Dict[[str](https://python.readthedocs.io/en/latest/library/stdtypes.html#str), Union[[dict](https://python.readthedocs.io/en/latest/library/stdtypes.html#dict), [types.Type](spanner_v1/types.md#google.cloud.spanner_v1.types.Type)]]]]]*) – List of DML statements, with optional params / param types. If passed, ‘params’ is a dict mapping names to the values for parameter replacement. Keys must match the names used in the corresponding DML statement. If ‘params’ is passed, ‘param_types’ must also be passed, as a dict mapping names to the type of value passed in ‘params’.
Return type

Tuple(status, Sequence[int])
Returns

Status code, plus counts of rows affected by each completed DML statement. Note that if the staus code is not OK, the statement triggering the error will not have an entry in the list, nor will any statements following that one.

begin()

Begin a transaction on the database.

Return type

bytes
Returns

the ID for the newly-begun transaction.
Raises

ValueError – if the transaction is already begun, committed, or rolled back.

commit()

Commit mutations to the database.

Return type

datetime
Returns

timestamp of the committed changes.
Raises

ValueError – if there are no mutations to commit.

committed( = Non )

Timestamp at which the transaction was successfully committed.

delete(table, keyset)

Delete one or more table rows.

Parameters
- table (str) – Name of the table to be modified.
- keyset (Keyset) – Keys/ranges identifying rows to delete.

execute_sql(sql, params=None, param_types=None, query_mode=None, query_options=None, partition=None, retry=

Perform an ExecuteStreamingSql API request.

Parameters
- sql (str) – SQL query statement
- params (dict, **{str -> column value}) – values for parameter replacement. Keys must match the names used in sql.
- param_types (dict[str -> Union[dict, *[types.Type](spanner_v1/types.md#google.cloud.spanner_v1.types.Type)]*]) – (Optional) maps explicit types for one or more param values; required if parameters are passed.
- query_mode (QueryMode) – Mode governing return of results / query plan. See: QueryMode.
- query_options – (Optional) Query optimizer configuration to use for the given query. If a dict is provided, it must be of the same form as the protobuf message QueryOptions
- partition (bytes) – (Optional) one of the partition tokens returned from partition_query().
Return type

StreamedResultSet
Returns

a result set instance which can be used to consume rows.
Raises

ValueError – for reuse of single-use snapshots, or if a transaction ID is already pending for multiple-use snapshots.

execute_update(dml, params=None, param_types=None, query_mode=None, query_options=None)

Perform an ExecuteSql API request with DML.

Parameters
- dml (str) – SQL DML statement
- params (dict, **{str -> column value}) – values for parameter replacement. Keys must match the names used in dml.
- param_types (dict[str -> Union[dict, *[types.Type](spanner_v1/types.md#google.cloud.spanner_v1.types.Type)]*]) – (Optional) maps explicit types for one or more param values; required if parameters are passed.
- query_mode (QueryMode) – Mode governing return of results / query plan. See: QueryMode.
- query_options (QueryOptions or dict) – (Optional) Options that are provided for query plan stability.
Return type

int
Returns

Count of rows affected by the DML statement.

insert(table, columns, values)

Insert one or more new table rows.

Parameters
- table (str) – Name of the table to be modified.
- columns (list of str) – Name of the table columns to be modified.
- values (list of lists) – Values to be modified.

insert_or_update(table, columns, values)

Insert/update one or more table rows.

Parameters
- table (str) – Name of the table to be modified.
- columns (list of str) – Name of the table columns to be modified.
- values (list of lists) – Values to be modified.

partition_query(sql, params=None, param_types=None, partition_size_bytes=None, max_partitions=None)

Perform a ParitionQuery API request.

Parameters
- sql (str) – SQL query statement
- params (dict, **{str -> column value}) – values for parameter replacement. Keys must match the names used in sql.
- param_types (dict[str -> Union[dict, *[types.Type](spanner_v1/types.md#google.cloud.spanner_v1.types.Type)]*]) – (Optional) maps explicit types for one or more param values; required if parameters are passed.
- partition_size_bytes (int) – (Optional) desired size for each partition generated. The service uses this as a hint, the actual partition size may differ.
- max_partitions (int) – (Optional) desired maximum number of partitions generated. The service uses this as a hint, the actual number of partitions may differ.
Return type

iterable of bytes
Returns

a sequence of partition tokens
Raises

ValueError – for single-use snapshots, or if a transaction ID is already associtated with the snapshot.

partition_read(table, columns, keyset, index='', partition_size_bytes=None, max_partitions=None)

Perform a ParitionRead API request for rows in a table.

Parameters
- table (str) – name of the table from which to fetch data
- columns (list of str) – names of columns to be retrieved
- keyset (KeySet) – keys / ranges identifying rows to be retrieved
- index (str) – (Optional) name of index to use, rather than the table’s primary key
- partition_size_bytes (int) – (Optional) desired size for each partition generated. The service uses this as a hint, the actual partition size may differ.
- max_partitions (int) – (Optional) desired maximum number of partitions generated. The service uses this as a hint, the actual number of partitions may differ.
Return type

iterable of bytes
Returns

a sequence of partition tokens
Raises

ValueError – for single-use snapshots, or if a transaction ID is already associtated with the snapshot.

read(table, columns, keyset, index='', limit=0, partition=None)

Perform a StreamingRead API request for rows in a table.

Parameters
- table (str) – name of the table from which to fetch data
- columns (list of str) – names of columns to be retrieved
- keyset (KeySet) – keys / ranges identifying rows to be retrieved
- index (str) – (Optional) name of index to use, rather than the table’s primary key
- limit (int) – (Optional) maximum number of rows to return. Incompatible with partition.
- partition (bytes) – (Optional) one of the partition tokens returned from partition_read(). Incompatible with limit.
Return type

StreamedResultSet
Returns

a result set instance which can be used to consume rows.
Raises

ValueError – for reuse of single-use snapshots, or if a transaction ID is already pending for multiple-use snapshots.

replace(table, columns, values)

Replace one or more table rows.

Parameters
- table (str) – Name of the table to be modified.
- columns (list of str) – Name of the table columns to be modified.
- values (list of lists) – Values to be modified.

rollback()

Roll back a transaction on the database.

update(table, columns, values)

Update one or more existing table rows.

Parameters
- table (str) – Name of the table to be modified.
- columns (list of str) – Name of the table columns to be modified.
- values (list of lists) – Values to be modified.