SQL · interview question
What is the healthiest performance judgment around joins?
Multiple choiceMediumchapter-11-curatedpremiumsqljoins
SELECT o.id, c.email
FROM orders o
JOIN customers c ON c.id = o.customer_id;Answer and explanation
Correct answer
D. Measure before optimizing, then change the part that actually dominates cost instead of guessing from style alone.
Why
Premature optimization is usually weaker than targeted optimization backed by measurement.
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