Implementing Type 2 with Effective Dates

Most candidates can explain Type 2 conceptually. The interview escalation is: 'Now implement it.' This is where candidates who have only read about Type 2 stall, and candidates who have built it in production accelerate. The Schema You Should Be Able to Write in 60 Seconds The MERGE Pattern: What the Interviewer Expects You to Produce The row_hash comparison is the key optimization. Without it, you would need to compare every tracked column in the WHERE clause. With it, a single hash comparison detects any change. This is the production pattern that interviewers want to see. The Follow-Up Trap The Point-in-Time Join: The Follow-Up They Always Ask