Transaction Processing

Serializability -- paper

A type of guarantee that transactions have some order, and that final state is deterministically reproducable by replaying transactions serially

• considered the highest level of isolation (ACID) between two transactions

Optimistic concurrency control -- paper

Concurrency control ensures correctness for systems that depend on concurrent operations

• optimisitic concurrency control assumes multiple transactions can usually be completed without interference
  • instead of locking resources, we forget about lock management and instead restart (or fail) a transaction whose underlying data has been changed since the transaction began

Two-phase Locking

Concurrency control method that guarantees serializability

Snapshot Isolation

A type of guarantee that reads be only made to a snapshot of the database until a transaction is fully completed, and then commit only if no updates conflict with any concurrent updates made since the snapshot

• main purpose is for better performance in comparison to serializability