Amazon Quantum Ledger Database (QLDB)

  • Fully managed ledger database that provides a transparent, immutable, and cryptographically verifiable transaction log ‎owned by a central trusted authority.
  • Used to track all application data changes, and maintain a complete and verifiable history of changes over time
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  • Amazon QLDB is serverless.  No capacity provisioning required or setting read/write limits.
  • QLDB transactions are ACID (atomicity, consistency, isolation, and durability) compliant.
  • Amazon QLDB uses PartiQL as its query language.

How it Works

amazon qldb

Common Use Cases

  • Finance
    • Banks can use Amazon QLDB to easily store an accurate and complete record of all financial transactions, instead of building a custom ledger with complex auditing functionality.
  • Insurance
    • Insurance companies can use Amazon QLDB to track the entire history of claim transactions. Whenever a conflict arises, Amazon QLDB can cryptographically verify the integrity of the claims data.

Components Of QLDB

  • Ledger
    • Consists of tables and journals that keep all of the immutable histories of changes in the table.
  • Tables 
    • Contains a collection of document revisions.
  • Journal
    • An immutable transactions log where transactions are appended as a sequence of blocks that are cryptographically chained together to provide a secure verification and immutability of the history of changes to your ledger data.
    • Only the data’s history of change cannot be altered and not the data itself.
  • Current State
    • The current state is similar to a traditional database where you can view and query the latest data.
  • History
    • The history is a table where you can view and query the history of all the data and every change ever made to the data.


  • Amazon QLDB can execute 2 – 3X as many transactions than ledgers in common blockchain frameworks.


  • Amazon QLDB automatically scales based on the workloads of your application.


  • Multiple copies of QLDB ledger are replicated across availability zones in a region. You can still continue to operate QLDB even in the case of zone failure.
  • Ensures redundancy within a region.
  • Also ensures full recovery when an availability zone goes down.

Backup and Restore

  • You can export the contents of your QLDB journals to S3 as a backup plan.


  • Amazon QLDB uses SHA-256 hash function to make a secure file representation of your data’s change history called digest. The digest serves as a proof of your data’s change history, enabling you to go back at a point in time to verify the validity and integrity of your data changes.
  • All data in transit and at rest are encrypted by default.
  • Uses AWS-owned keys for encryption of data.
  • The authentication is done by attaching a signature to the HTTP requests. The signature is then verified using the AWS credentials.
  • Integrated with AWS Private Link.


  • You are billed based on five categories
    • Write I/Os
      • Pricing per 1 million requests
    • Read I/Os
      • Pricing per 1 million requests
    • Journal Storage Rate
      • Pricing per GB-month
    • Indexed Storage Rate
      • Pricing per GB-month
    • Data Transfer OUT From Amazon QLDB To Internet
      • You are charged based on the amount of data transferred per month. The rate varies for different regions.


  • Amazon QLDB does not support Backup and Restore. But you can export your data from QLDB to S3.
  • Does not support Point-in-time restore feature.
  • Does  not support cross-region replication.
  • Does not support the use of customer managed CMKs (Customer Managed Keys).

Note: If you are studying for the AWS Certified Database Specialty exam, we highly recommend that you take our AWS Certified Database – Specialty Practice Exams and read our Database Specialty exam study guide.

AWS Certified Database Specialty Practice Exams


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