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Hand-written tutorials, ordered as a recommended learning path.

1. 41 Row-Level Security Learn how PostgreSQL row-level security works, how to write effective policies, and how to enforce per-tenant isolation safely in multi-tenant applications. 4 min read →
2. 42 Procs vs Funcs When to use stored procedures, when to use functions, and how transaction control, return values, and side effects differ across major databases. 4 min read →
3. 43 Transactions Understand BEGIN, COMMIT, ROLLBACK, and the four standard isolation levels with concrete examples of dirty reads, non-repeatable reads, and phantoms. 5 min read →
4. 44 Windows Learn how window functions work in SQL, when to use ROW_NUMBER, RANK, LAG, and SUM OVER, and how they differ from GROUP BY. 5 min read →
5. 45 Postgres EXPLAIN Learn how to read Postgres EXPLAIN and EXPLAIN ANALYZE output, spot expensive operations, and apply practical indexing and rewrite techniques to speed up queries. 6 min read →
6. 46 Normalization A practical guide to database normalization with real customer and order examples. Covers 1NF, 2NF, 3NF, when to denormalize, and tradeoffs. 6 min read →
7. 47 Window Functions Learn SQL window functions with practical examples. Covers ROW_NUMBER, RANK, DENSE_RANK, LAG, LEAD, running totals, and the OVER clause in depth. 6 min read →