GROUP BY Fundamentals: Performance

**Performance Tips:**

- Index GROUP BY columns

- Filter with WHERE before GROUP BY

- Avoid GROUP BY on large text columns

- Consider covering indexes

Index GROUP BY columns

Filter with WHERE to reduce rows

Avoid GROUP BY on large text columns

Use covering indexes

Selecting non-grouped columns without aggregates

Forgetting to GROUP BY all non-aggregate columns

Not indexing GROUP BY columns

Confusing WHERE and HAVING