1 00:00:00,550 --> 00:00:02,910 ‫Now let's talk about Amazon QLDB, 2 00:00:02,910 --> 00:00:06,800 ‫which stands for Quantum Ledger Database. 3 00:00:06,800 --> 00:00:07,730 ‫So what is it? 4 00:00:07,730 --> 00:00:11,070 ‫A ledger is a book recording financial transactions 5 00:00:11,070 --> 00:00:13,820 ‫and so QLDB is going to be just to have a ledger 6 00:00:13,820 --> 00:00:15,160 ‫of financial transactions. 7 00:00:15,160 --> 00:00:17,120 ‫It's a fully managed database, it's serverless, 8 00:00:17,120 --> 00:00:19,240 ‫highly available, and has replication of data 9 00:00:19,240 --> 00:00:21,160 ‫across three availability T zones. 10 00:00:21,160 --> 00:00:24,090 ‫And it's used to review history of all the changes 11 00:00:24,090 --> 00:00:25,710 ‫made to your application data over time, 12 00:00:25,710 --> 00:00:27,890 ‫that's why it's called a ledger. 13 00:00:27,890 --> 00:00:30,170 ‫So it's an immutable system as well, 14 00:00:30,170 --> 00:00:32,823 ‫that means that once you write something to the database, 15 00:00:32,823 --> 00:00:35,400 ‫it can not be removed or modified. 16 00:00:35,400 --> 00:00:39,013 ‫And there is also a way to have a cryptographic signature 17 00:00:39,013 --> 00:00:42,180 ‫to make sure that indeed nothing has been removed. 18 00:00:42,180 --> 00:00:43,960 ‫So how does it work? 19 00:00:43,960 --> 00:00:46,480 ‫Well, there is behind the scenes a journal, 20 00:00:46,480 --> 00:00:49,150 ‫and so a journal has a sequence of modifications. 21 00:00:49,150 --> 00:00:51,820 ‫And so anytime a modification is made, 22 00:00:51,820 --> 00:00:55,030 ‫there is a cryptographic hash that is computed 23 00:00:55,030 --> 00:00:58,500 ‫which guarantees that nothing has been deleted or modified 24 00:00:58,500 --> 00:01:01,670 ‫and so this can be verified by anyone using the database. 25 00:01:01,670 --> 00:01:04,550 ‫So this is extremely helpful for financial transactions 26 00:01:04,550 --> 00:01:05,810 ‫because you wanna make sure that 27 00:01:05,810 --> 00:01:08,290 ‫obviously no financial transaction 28 00:01:08,290 --> 00:01:10,100 ‫is disappearing from your database 29 00:01:10,100 --> 00:01:13,770 ‫which makes QLDB a great ledger database in the cloud. 30 00:01:13,770 --> 00:01:16,400 ‫So you get two to three times better performance 31 00:01:16,400 --> 00:01:18,540 ‫than common ledger blockchain frameworks 32 00:01:18,540 --> 00:01:21,750 ‫and also you can manipulate data using SQL. 33 00:01:21,750 --> 00:01:22,940 ‫Now, as you'll see in the next lecture 34 00:01:22,940 --> 00:01:25,160 ‫there's also another database technologies 35 00:01:25,160 --> 00:01:27,540 ‫called Amazon Managed Blockchain. 36 00:01:27,540 --> 00:01:30,720 ‫But the difference between QLDB and Managed Blockchain 37 00:01:30,720 --> 00:01:35,146 ‫is that with QLDB, there is no concept of decentralization. 38 00:01:35,146 --> 00:01:37,280 ‫That means that there's just a central database 39 00:01:37,280 --> 00:01:40,280 ‫owned by Amazon that allows you to write this journal. 40 00:01:40,280 --> 00:01:41,113 ‫Okay. 41 00:01:41,113 --> 00:01:43,917 ‫And this is in line with many financial regulation rules. 42 00:01:43,917 --> 00:01:47,090 ‫So the difference between QLDB and Managed Blockchain 43 00:01:47,090 --> 00:01:50,420 ‫is that QLDB has a central authority component 44 00:01:50,420 --> 00:01:53,070 ‫and it's a ledger, whereas managed blockchain 45 00:01:53,070 --> 00:01:55,930 ‫is going to have a de-centralization component as well. 46 00:01:55,930 --> 00:01:56,763 ‫Okay. 47 00:01:56,763 --> 00:01:58,942 ‫So that's it, anytime you see financial transactions 48 00:01:58,942 --> 00:02:01,610 ‫and ledger, think QLDB. 49 00:02:01,610 --> 00:02:03,360 ‫I will see you in the next lecture.