Your sales dashboard says there are 500 units in stock. Run a query against production and you get 12. Nobody broke anything. The nightly batch job ran nine hours ago, and in those nine hours the product sold out.

Change Data Capture (CDC) is the standard way to close that gap without hammering your production database. This post walks through how it works, what the events look like, a real Postgres to Snowflake pipeline, and the mistakes that tend to show up only once the pipeline is live.

Prefer to watch? Here's the 6-minute video version with animated diagrams:

Video link: Change Data Capture (CDC) Explained in 6 Minutes

What CDC actually means

CDC means you treat every row-level change in a source database as an event. When a row is inserted, updated or deleted, you capture that change in the order it was committed and send it to whatever needs it downstream: a warehouse like Snowflake, a search index, a cache, or another service.

The point is to stop copying the whole table every run.…