This is the entry point for all interactions with Amazon QLDB.

In order to start using the driver, you need to instantiate it with a ledger name:

let qldbDriver: QldbDriver = new QldbDriver(your-ledger-name);

You can pass more parameters to the constructor of the driver which allow you to control certain limits to improve the performance. Check the constructor to see all the available parameters.

A single instance of the QldbDriver is attached to only one ledger. All transactions will be executed against the ledger specified.

The driver exposes executeLambda method which should be used to execute the transactions. Check the executeLambda method for more details on how to execute the Transaction.


  • QldbDriver



_isClosed: boolean
_ledgerName: string
_maxConcurrentTransactions: number
_qldbClient: QLDBSessionClient
_retryConfig: RetryConfig
_semaphore: default
_sessionPool: QldbSession[]


  • This is a driver shutdown method which closes all the sessions and marks the driver as closed. Once the driver is closed, no transactions can be executed on that driver instance.

    Note: There is no corresponding open method and the only option is to instantiate another driver.

    Returns void

  • This is the primary method to execute a transaction against Amazon QLDB ledger.

    When this method is invoked, the driver will acquire a Transaction and hand it to the TransactionExecutor you passed via the transactionFunction parameter. Once the transactionFunction's execution is done, the driver will try to commit the transaction. If there is a failure along the way, the driver will retry the entire transaction block. This would mean that your code inside the transactionFunction function should be idempotent.

    You can also return the results from the transactionFunction. Here is an example code of executing a transaction

    let result = driver.executeLambda(async (txn:TransactionExecutor) => {
    let a = await txn.execute("SELECT a from Table1");
    let b = await txn.execute("SELECT b from Table2");
    return {a: a, b: b};

    Please keep in mind that the entire transaction will be committed once all the code inside the transactionFunction is executed. So for the above example the values inside the transactionFunction, a and b, are speculative values. If the commit of the transaction fails, the entire transactionFunction will be retried.

    The function passed via retryIndicator parameter is invoked whenever there is a failure and the driver is about to retry the transaction. The retryIndicator will be called with the current attempt number.


    DriverClosedError When a transaction is attempted on a closed driver instance. close


    ClientException When the commit digest from commit transaction result does not match.


    SessionPoolEmptyError When maxConcurrentTransactions limit is reached and there is no session available in the pool.


    InvalidSessionException When a session expires either due to a long-running transaction or session being idle for long time.


    BadRequestException When Amazon QLDB is not able to execute a query or transaction.

    Type Parameters

    • T


    • transactionLambda: ((transactionExecutor: TransactionExecutor) => Promise<T>)

      The function representing a transaction to be executed. Please see the method docs to understand the usage of this parameter.

    • Optional retryConfig: RetryConfig

      Config to specify max number of retries, base and custom backoff strategy for retries. This config overrides the retry config set at driver level for a particular lambda execution. Note that all the values of the driver level retry config will be overridden by the new config passed here.

    Returns Promise<T>

  • A helper method to get all the table names in a ledger.


    Promise which fulfills with an array of table names.

    Returns Promise<string[]>

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