Given a users table with 10M rows and these common queries: (1) SELECT * WHERE email = ?, (2) SELECT * WHERE last_name = ? AND first_name = ?, (3) SELECT * WHERE created_at > ? ORDER BY created_at, (4) SELECT * WHERE city = ? AND age BETWEEN ? AND ?, (5) Full-text search on bio. Design indexes: which columns, what type (B-tree, hash, full-text), composite vs single-column. Explain tradeoffs (read vs write performance).
