‫Now let's talk about Amazon QLDB,
‫which stands for Quantum Ledger Database.
‫So what is it?
‫A ledger is a book recording financial transactions
‫and so QLDB is going to be just to have a ledger
‫of financial transactions.
‫It's a fully managed database, it's serverless,
‫highly available, and has replication of data
‫across three availability T zones.
‫And it's used to review history of all the changes
‫made to your application data over time,
‫that's why it's called a ledger.
‫So it's an immutable system as well,
‫that means that once you write something to the database,
‫it can not be removed or modified.
‫And there is also a way to have a cryptographic signature
‫to make sure that indeed nothing has been removed.
‫So how does it work?
‫Well, there is behind the scenes a journal,
‫and so a journal has a sequence of modifications.
‫And so anytime a modification is made,
‫there is a cryptographic hash that is computed
‫which guarantees that nothing has been deleted or modified
‫and so this can be verified by anyone using the database.
‫So this is extremely helpful for financial transactions
‫because you wanna make sure that
‫obviously no financial transaction
‫is disappearing from your database
‫which makes QLDB a great ledger database in the cloud.
‫So you get two to three times better performance
‫than common ledger blockchain frameworks
‫and also you can manipulate data using SQL.
‫Now, as you'll see in the next lecture
‫there's also another database technologies
‫called Amazon Managed Blockchain.
‫But the difference between QLDB and Managed Blockchain
‫is that with QLDB, there is no concept of decentralization.
‫That means that there's just a central database
‫owned by Amazon that allows you to write this journal.
‫Okay.
‫And this is in line with many financial regulation rules.
‫So the difference between QLDB and Managed Blockchain
‫is that QLDB has a central authority component
‫and it's a ledger, whereas managed blockchain
‫is going to have a de-centralization component as well.
‫Okay.
‫So that's it, anytime you see financial transactions
‫and ledger, think QLDB.
‫I will see you in the next lecture.