Day 11: AWS Solutions Architect Professional Prep – Database Migration & Global Databases

In today’s digital world, customers won’t wait for slow pages, and businesses can’t afford downtime or data loss. The bar of expected speed, uptime, and reliability are at an all-time high.

To that end AWS provides powerful, fully managed tools to help you move data safely, serve users globally, and recover instantly when things go wrong.

This lesson aims at breaking down how AWS makes database migration and global replication simple.

Here are four key questions (and answers) that explain how AWS helps organizations handle data movement, migration, and global access without the headaches.

1. How do we move an existing database to the cloud without interrupting the business?

We can use the “digital moving truck”, AWS Database Migration Service (DMS). How does it work? DMS first copies everything from your existing database (a “Full Load”).

Then it switches to Change Data Capture (CDC) to constantly track new transactions, sign-ups, or orders as they happen. The CDC mode allows the old database to keep running while the new one is built. DMS simply copies every new change and transaction in real-time until you’re ready to switch over.The real-time replication ensures that when you switch to the cloud version, all your data is up to date and downtime is close to zero. It is simple, smooth, and reliable. Think of the moving truck taking the furniture to your new house and then watching the old house and sending over any new mail or package deliveries in near real-time.

DMS  can move data between homogeneous databases ie. the exact same type of database (like moving from one type of MySQL to another) or between heterogeneous databases ie. different types (like moving from an Oracle database to a PostgreSQL database)

2. What if our new cloud database speaks a different “language”?

The AWS Schema Conversion Tool (SCT) handles the translation for heterogeneous migration.SCT converts the structure, code, functions, and rules (the schema) from one type of database to another during a heterogeneous migration. It also gives you a report card on how hard the translation will be. To illustrate, if you move from a foreign country (like Oracle) to a new one (like Aurora PostgreSQL), you don’t just move your furniture; you need to translate your legal documents and instructions.

So, the 2 main tools we need for moving the house (migration) are AWS Database Migration Service (DMS), The Data Mover and AWS Schema Conversion Tool (SCT) The Language Translator. Together, they make cloud migration seamless.

3. How do we make our database fast for users all over the world?

We can use Aurora Global Database, the global relational powerhouse. It is best for relational data (like account records or complex sales transactions). The idea is : One primary region handles all new writes and up to five secondary regions hold live read-only copies. These replicas are updated with sub-second latency, so users in Europe, Asia, or America get lightning-fast responses.

If our main region fails, a secondary one can be promoted in under a minute (RTO < 1 minute), thus keeping global operations alive.

4. What if users need to write data from any region, anytime?

We can use DynamoDB Global Tables. It is best used for high-speed, simple data (like user profiles or gaming scores). How does it work? You set up servers in multiple regions, and all of them can accept new transactions simultaneously (active-active). In other words, every region can handle both reads and writes. Each change made anywhere is instantly copied everywhere.DynamoDB automatically keeps the most recent one, the “last writer wins” rule which is the perfect setup for real-time, global applications like gaming, finance, or user profiles where every millisecond counts.

Expressed differently, If two regions try to change the same record at the exact same moment, the system resolves it automatically by accepting the change that arrived last and there is no manual failover needed for disaster recovery; it’s built-in since all regions can handle writes.

The bottomline is that mastering database migration and global design on AWS is about knowing which tool fits your need. Need to move existing databases with minimal downtime? Use AWS DMS. Need to translate database code and structure? Use AWS SCT Need Global relational performance? Use Aurora Global Database. Need Global NoSQL with multi-region writes? Use DynamoDB Global Tables. Thanks to these tools an organization can move data smoothly and build highly resilient, super-fast applications accessible to anyone, anywhere in the world.