How does the Serializable mechanism determine the order and inclusion of transactions when saving them to a database?

The Serializable transaction isolation mechanism provides the strictest level of isolation, where transactions are executed as if they were sequential (one after another), even if they are actually executed in parallel.

To achieve this, DBMSs use various methods, such as:

• Locks: transactions lock rows or tables so that other transactions cannot read or modify data until the current transaction is completed.
• Multiversion Concurrency Control (MVCC): versions of data are created so that transactions see a consistent state of the database without conflicts.

The order of transaction execution is determined to avoid anomalies (such as phantom reads, non-repeatable reads). If a conflict occurs, one of the transactions is rolled back.

Thus, Serializable guarantees that the result of parallel transaction execution is equivalent to some serial order of their execution, ensuring data integrity.