MVCC

The core competency of the database engine is gauged by its adherence to multi-version concurrency control (MVCC) transaction processing procedures and protocols. MVCC enables multiple user transactions to access the data concurrently for select, insert, update, and delete operations using ANSI-compliant isolation levels, which include READ UNCOMMITTED, READ COMMITTED, REPEATABLE READ, or SERIALIZABLE. Dirty reads are possible with READ UNCOMMITTED transactions, whereas READ COMMITTED reads committed data, avoiding dirty reads.