SQL Patterns That Scale

Writing SQL that works is easy. Writing SQL that scales is a discipline.

Indexing Strategy

Indexes are not free. Every index speeds up reads but slows down writes. Index the columns in your WHERE clauses and JOIN conditions.

Query Patterns

• Use EXISTS instead of IN for subqueries
• Avoid SELECT * in production
• Use EXPLAIN ANALYZE to understand query plans
• Paginate with keyset pagination for large datasets

Schema Design

Normalise first, denormalise intentionally. Start with a clean relational model, then introduce denormalisation only with measured evidence.