What is the high efficiency of SERIALIZABLE isolation level in PostgreSQL?

The SERIALIZABLE isolation level in PostgreSQL provides maximum transaction isolation, ensuring that the result of concurrent transaction execution is equivalent to some sequential order of their execution. High efficiency is achieved through the use of the Serializable Snapshot Isolation (SSI) mechanism, which allows transactions to operate in parallel without excessive blocking, while detecting potential conflicts and preventing anomalies.

Unlike traditional locking serialization, SSI reduces the number of locks and waits, increasing performance while maintaining strict isolation. When a conflict is detected, one of the transactions is rolled back, ensuring data integrity without unnecessary locking.

Thus, high efficiency lies in the balance between strict isolation and parallelism, implemented through SSI in PostgreSQL.