Based on technology built internally at Amazon, the tech giant's newest database provides a centralized approach for enabling a cryptographically secure ledger system.
The database provides a cryptographically secured ledger as a managed service. It can be used to store both structured and unstructured data, providing what Amazon refers to as an immutable transaction log.
The new database service was released on Sept. 10, 10 months after AWS introduced it as a preview technology.
"This is useful for establishing a system of record and for satisfying various types compliance requirements, such as regulatory compliance," Litan said. "Gartner estimates that QLDB and other competitive offerings that will eventually emerge will gain at least 20% of permissioned blockchain market share over the next three years."
A permissioned blockchain has a central authority in the system to help provide overall governance and control. Litan sees the Quantum Ledger Database as satisfying several key requirements in multi-company projects, which are typically complementary to existing database systems.
Among the requirements is that once data is written to the ledger, the data is immutable and cannot be deleted or updated. Another key requirement that QLDB satisfies is that it provides a cryptographically and independently verifiable audit trail.
"These features are not readily available using traditional legacy technologies and are core components to user interest in adopting blockchain and distributed ledger technology," Litan said. "In sum, QLDB is optimal for use cases when there is a trusted authority recognized by all participants and centralization is not an issue."
Diagram of how AWS Quantum Ledger Database works
Centralized ledger vs. de-centralized blockchain
The basic promise of many blockchain-based systems is that they are decentralized, and each party stores a copy of the ledger. For a transaction to get stored in a decentralized and distributed ledger, multiple parties have to come to a consensus. In this way, blockchains achieve trust in a distributed and decentralized way.
"Customers who need a decentralized application can use Amazon Managed Blockchain today," said Rahul Pathak, general manager of databases, analytics and blockchain at AWS. "However, there are customers who primarily need the immutable and verifiable components of a blockchain to ensure the integrity of their data is maintained."
By quantum, we imply indivisible, discrete changes. In QLDB, all the transactions are recorded in blocks to a transparent journal where each block represents a discrete state change.
Rahul PathakGeneral manager of databases, analytics and blockchain, Amazon Web Services
For customers who want to maintain control and act as the central trusted entity, just like any database application works today, a decentralized system with multiple entities is not the right fit for their needs, Pathak said.
"Amazon [Quantum Ledger Database] combines the data integrity capabilities of blockchain with the ease and simplicity of a centrally owned datastore, allowing a single entity to act as the central trusted authority," Pathak said.
While QLDB includes the term "quantum" in its name, it's not a reference to quantum computing.
"By quantum, we imply indivisible, discrete changes," Pathak said. "In QLDB, all the transactions are recorded in blocks to a transparent journal where each block represents a discrete state change."
How the Amazon Quantum Ledger Database works
The immutable nature of QLDB is a core element of the database's design. Pathak explained that QLDB uses a cryptographic hash function to generate a secure output file of the data's change history, known as a digest. The digest acts as a proof of the data's change history, enabling customers to look back and validate the integrity of their data changes.
From a usage perspective QLDB supports the PartiQL open standard query language that supports SQL-compatible access to data. Pathak said that customers can build applications with the Amazon QLDB Driver for Java to write code that accesses and manipulates the ledger database.
"This is a Java driver that allows you to create sessions, execute PartiQL commands within the scope of a transaction, and retrieve results," he said.
Developed internally at AWS
The Quantum Ledger Database is based on technology that AWS has been using for years, according to Pathak. AWS has been using an internal version of Amazon QLDB to store configuration data for some of its most critical systems, and has benefitted from being able to view an immutable history of changes, he said.
"Over time, our customers have asked us for the same ledger capability, and a way to verify that the integrity of their data is intact," he said. "So, we built Amazon QLDB to be immutable and cryptographically verifiable."
