Can you explain what the Serializable isolation level means in the context of database transactions?

The Serializable isolation level is the strictest level of transaction isolation in databases. It guarantees that the concurrent execution of transactions is equivalent to some serial (sequential) execution, meaning as if transactions were executed one after another.

This prevents all major concurrency anomalies such as:

• phantom reads,
• non-repeatable reads,
• dirty reads.

In practice, this is achieved through locks or other mechanisms that prevent transactions from seeing intermediate changes made by other transactions and do not allow conflicting changes to occur simultaneously.

The drawback is that it can lead to locking and reduced performance due to waiting for resources to be released.

An example in Java using JDBC:

connection.setTransactionIsolation(Connection.TRANSACTION_SERIALIZABLE);
connection.setAutoCommit(false);
// perform operations within the transaction
connection.commit();