[FAQ Bot] NEW: When should I use merge instead of append?

_questions/data-engineering-zoomcamp/module-3/060_2442e32be2_merge-vs-append-data-ingestion.md

@@ -0,0 +1,21 @@
+---
+id: 2442e32be2
+question: When should I use merge instead of append?
+sort_order: 60
+---
+
+Use `merge` when existing data can be updated. If a record with the same primary key already exists, it will be updated. If it does not exist, it will be inserted.
+
+Common use cases:
+- Order status updates
+- User profile changes
+- CDC-based data processing
+
+```yaml
+materialization:
+type: merge
+primary_key: order_id
+```
+
+If data never changes, use `append`.
+If data can change, use `merge`.