SQL Indexes That Actually Help
How to think about indexes from query shape, cardinality, ordering, and write cost.
SQL
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Bad SQL That Looks Fine in Development
Queries that pass locally can still fail in production when data volume and concurrency appear.
Transactions Are Not Optional in Money Flows
Where transactions, locks, idempotency, and audit records matter in financial-style systems.
Database Schema Design Is Product Design
Tables, constraints, and names shape what the product can safely become.
Pagination: Offset, Cursor, and Why Users Feel the Difference
Choosing pagination based on consistency, performance, and user experience.
Read EXPLAIN Plans Before Adding Random Indexes
A practical habit for understanding query plans instead of guessing.