What level of isolation did you use in your project?

In my projects, the most commonly used isolation level was READ COMMITTED. It ensures that a transaction only sees committed data, preventing dirty reads. This provides a good balance between performance and data integrity for most business applications.

In some cases, when stricter consistency is required, the REPEATABLE READ level was used to avoid non-repeatable reads and phantom records.

The choice of isolation level depends on the requirements for data consistency and performance. For example:

• READ UNCOMMITTED — the lowest level, rarely used due to the risk of dirty reads.
• SERIALIZABLE — the strictest, providing full isolation but potentially reducing performance significantly.

It is important to consider the features of the DBMS and the load when choosing the isolation level.