Spanner read-write transaction support.
Implement read-write transaction semantics for a session.
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 mutations to the database.
Return type: datetime Returns: timestamp of the committed changes. Raises:
ValueErrorif there are no mutations to commit.
Timestamp at which the transaction was successfully committed.
Roll back a transaction on the database.