Transaction Reference

class pyqldb.transaction.transaction.Transaction(session, read_ahead, transaction_id, executor)[source]

A class representing a QLDB transaction.

Every transaction is tied to a parent (Pooled)QldbSession, meaning that if the parent session is closed or invalidated, the child transaction is automatically closed and cannot be used. Only one transaction can be active at any given time per parent session, and thus every transaction should call pyqldb.transaction.transaction.Transaction.abort() or pyqldb.transaction.transaction.Transaction.commit() when it is no longer needed, or when a new transaction is desired from the parent session.

An InvalidSessionException indicates that the parent session is dead, and a new transaction cannot be created without a new (Pooled)QldbSession being created from the parent driver.

Any unexpected errors that occur within a transaction should not be retried using the same transaction, as the state of the transaction is now ambiguous.

When an OCC conflict occurs, the transaction is closed and must be handled manually by creating a new transaction and re-executing the desired queries.

Child Cursor objects will be closed when the transaction is aborted or committed.

  • session (pyqldb.communication.session_client.SessionClient) – The session object representing a communication channel with QLDB.

  • read_ahead (int) – The number of read-ahead buffers used in retrieving results.

  • transaction_id (str) – The ID of a transaction.

  • executor (concurrent.futures.thread.ThreadPoolExecutor) – The executor to be used by the retrieval thread.


Abort this transaction and close child cursors. No-op if already closed by commit or previous abort.


Close this transaction.


Commit this transaction and close child cursors.

  • IllegalStateError – When the commit digest from commit transaction result does not match.

  • TransactionClosedError – When this transaction is closed.

  • ClientError – When there is an error communicating against QLDB.

execute_statement(statement, *parameters)[source]

Execute the statement.

  • statement (str/function) – The statement to execute.

  • parameters (Variable length argument list) –

    Ion values or Python native types that are convertible to Ion for filling in parameters of the statement.

    Details on conversion support and rules.

Return type



Cursor on the result set of the statement.

  • TransactionClosedError – When this transaction is closed.

  • ClientError – When there is an error executing against QLDB.

  • TypeError – When conversion of native data type (in parameters) to Ion fails due to an unsupported type.

property is_closed

The read-only flag indicating if this transaction has been committed or aborted.

property transaction_id

The read-only ID of this transaction.