When working with data, staying up to date is essential. New customers, updated prices, or deleted records are all changes that can occur, and you want your system to know what changed, and when.
The process of capturing the information about what has changed is Change Data Capture, or CDC.
What is CDC?
Imagine your database is like a notebook, and every time something changes (cross out a word, add a new line, rub out a line) you want to keep track of what changed and when. CDC is like a change log stuck to the back of that notebook, automatically recording what was added, updated, or deleted, and when.
How does it work?
CDC systems monitor transaction logs in your database, and from from there, CDC captures:
- What changed
- When it changed
- Sometimes who changed it
- Any other useful metadata
It gives you a play-by-play of how the data got to where it is; if you have the original data and the change logs, you could reproduce the current data!
Or, if you have the current data and the change logs, you can roll back by undoing what happened in the change logs.
Where does this captured data go?
This depends on the system - CDC is a conceptual approach, not one fixed system. The changed data could be:
- Sent to a data warehouse
- Read into a dashboard
- Used to sync systems
- Or trigger alerts for downstream processes
Why is CDC useful?
CDC is powerful when:
- You want to roll back a database
- You want real-time or near real-time updates
- You’re syncing data between systems (recreating a database from change logs)
- You need audit trails or history of changes
- You’re avoiding slow and expensive full refreshes
Summary:
Change Data Capture lets you keep your data in sync and up-to-date by tracking what changed, when, and how.