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Walk me through reading an EXPLAIN ANALYZE plan to find why a query is slow.

Everyone says 'add an index,' but a strong engineer reads the plan first. The signal is finding the dominant operator, comparing estimated vs actual rows, and recognizing the seq-scan, bad-join, and spill patterns.

Updated Aug 2026 · Grounded in real Applied AI Engineer interview loops and written to a senior-engineer editorial bar.

Everyone says 'add an index,' but a strong engineer reads the plan first. The signal is finding the dominant operator, comparing estimated vs actual rows, and recognizing the seq-scan, bad-join, and spill patterns.

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