Alex Merced • 4/29/2026

Concurrency, Isolation, and MVCC: How Engines Handle Contention

This article is part 10 of a series on query engine design, focusing on how database engines handle concurrency, isolation, and contention. It covers the core problem of lost updates, two-phase locking (2PL) with its strengths and weaknesses, Multi-Version Concurrency Control (MVCC) for non-blocking reads, isolation levels, optimistic concurrency control (OCC), and how lakehouse table formats handle concurrency. It also discusses real-world tradeoffs and provides further reading. The content is technical, aimed at software engineers and database enthusiasts.

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#Mvcc #Concurrency Control #Database Locking