Amazon Quantum Ledger Database (QLDB)

Utkarsh Mehta

3 min readJun 16, 2020

On June 5th 2020 Amazon open-sourced the node.js drivers for QLDB on Github.

awslabs/amazon-qldb-driver-nodejs

A NodeJs implementation of a driver for Amazon QLDB. - awslabs/amazon-qldb-driver-nodejs

github.com

Amazon also released a new query language called PartiQL for QLDB.

Amazon QLDB PartiQL Reference

Information about elements of the PartiQL query language that are supported in Amazon QLDB.

docs.aws.amazon.com

So what is Quantum Ledger Database (QLDB) and how it is different from traditional databases.

The main goal of QLDB is to track the history of changes happened on the data while maintaining the integrity of data. The history of changes is immutable and verifiable.

Immutability and verifiably are the core features of Blockchain. With the rise of Blockchain based solutions a lots of new projects tried to leverage blockchain as database for critical data, but as blockchain is distributed and there is a consensus process involved before adding new blocks to chain, there were issues like speed, scalability, size of blockchain etc.

QLDB does this a bit differently, firstly QLDB is centralised unlike blockchains.

QLDB consists of following components:

Current State :- Current State is nothing but traditional database with the latest data.
History Data :- In history data different versions of a particular unit of data is stored. For every update a new version is created and added to history data.
Journal :- To maintain an immutable copy of all the changes history data is linked using SHA256 hash of data making the history cryptographically verifiable.

The Journal can be considered as a centralised blockchain, linking block of data using their hashes making it immutable.

QLDB is serverless so it is scalable by design and suitable for applications of all types of traffic.

Amazon introduced PartiQL a new query language which is database, vendor, data format and data model agnostic.

Announcing PartiQL: One query language for all your data | Amazon Web Services

Data is being gathered and created at rates unprecedented in history. Much of this data is intended to drive business…

aws.amazon.com

Most effective uses for QLDB will be for the applications where data integrity and the history of changes in the data both are utmost important.

To mention a few industries banking, supply chain, medical, production etc can utilise QLDB effectively.

Conclusion:

QLDB is definitely a good implementation using immutability of blockchain and scalability of serverless technology.