# Transaction Isolation Level

A setting defining which effects of concurrent transactions may be observed.

## What is **Transaction Isolation Level** in a relational database?

**Transaction Isolation Level** — A setting defining which effects of concurrent transactions may be observed.

```sql
SET TRANSACTION ISOLATION LEVEL SERIALIZABLE;
```

Level: Journeyman · [More Database terms at this level](https://www.ask-codey.com/glossary/subjects/database/journeyman)

Updated: September 27, 2026

Source: https://www.ask-codey.com/glossary/transaction-isolation-level