Multiversion Concurrency Control (MVCC) provides concurrent access to the database without locking the data so that readers do not block writers and writers do not block readers. MVCC improves the performance of database applications in a multiuser environment.

MVCC provides each user connected to the database with a consistent point in time "snapshot" of the data. Other users of the database do not see any changes until the transaction is committed.

Conceptually, MVCC is like row locking, but without the need for page or row read locks.

When using MVCC, applications see better performance because no read locking is required; the application does not have to wait to acquire a lock.