What does the Serializable isolation level in transactions mean and how does it affect data processing?

The Serializable isolation level is the strictest level of transaction isolation in databases. It guarantees that the result of executing multiple concurrent transactions will be the same as if they were executed sequentially, one after another.

This prevents issues such as:

• "dirty read",
• non-repeatable read,
• phantom read.

In practice, this means that at the Serializable level, transactions lock data to prevent conflicts and ensure data integrity, but this can reduce performance due to locking and waiting.

Example: if two transactions try to update the same records simultaneously, one will wait for the other to finish to avoid conflicts.