Database Migration -

The application is updated to write data to both the old and new databases simultaneously. This keeps the new system "warm" and up-to-date.

Never underestimate how long a "temporary" hack or data transfer will take. If the move goes wrong, rolling back is a nightmare. Chapter 2: The Strategy—Phased Migration

This is a full story about —a high-stakes, technical, and often terrifying saga that every growing tech company eventually faces. database migration

You must map every dependency—every table, view, and stored procedure.

Despite the best planning, migrations are "10x more difficult than people think". The application is updated to write data to

For a high-traffic app, "turning it off" for 4 hours costs millions in revenue and causes massive customer anger.

Early attempts to move often look like a "Big Bang" approach. You turn off the application, copy the database, and turn it on in the new location. If the move goes wrong, rolling back is a nightmare

Imagine a startup, "FastFlow," that started with a simple, comfortable home: a single MySQL database on a modest server. As years passed, the family (users) grew, and they bought more furniture (data). Now, the house is bursting at the seams, the floor is sagging, and the plumbing (query performance) is failing. It’s time to move to a massive new mansion (cloud-native PostgreSQL on AWS).