SQL pattern · 10 problems

Incremental merge & CDC

Graded problems on incremental merge & CDC, from easy to hard.

10 problems · about 2 h 20 min in all

Start with problem 01Which source keys a MERGE would insert · 8 min

Easy

3 problems · about 26 min

01Which source keys a MERGE would insert8 min →02Pick up the next incremental batch8 min →03Count active subscriptions when rows are soft-deleted10 min →

Medium

4 problems · about 57 min

04Classify each source key: insert or matched12 min →05Rebuild current state from a CDC change log15 min →06Predict the table a MERGE leaves behind15 min →07Count inserts, updates and deletes between two snapshots15 min →

Hard

3 problems · about 57 min

08Find the keys that would break a MERGE12 min →09Apply a batch to an SCD2 dimension25 min →10Select a safe incremental batch with late, duplicated events20 min →