Change Data Capture

1. The Incident

This lesson has been promised for half the course. Its incident has already happened to you four times:

• The CQRS lesson's search index was dual-written from app code. It silently diverged when Elasticsearch calls timed out during a deploy. Orders were findable in the database and missing from search.
• The cache-aside lesson's bulk import wrote straight to the database and invalidated nothing. Products were stale for an hour, "randomly."