🎁 New User? Get 20% off your first purchase with code NEWUSER20 · ⚡ Instant download · 🔒 Secure checkout Register Now →
Menu

Categories

Databases Advanced

What is MVCC (Multi-Version Concurrency Control)?

A technique where the database maintains multiple versions of data to allow concurrent reads and writes without locking.

MVCC enables high concurrency by letting readers see a consistent snapshot of data without blocking writers. When a row is updated, the database creates a new version rather than overwriting the old one. Readers see the version that was current when their transaction started. PostgreSQL implements MVCC by storing version information (xmin/xmax transaction IDs) with each tuple. This eliminates read-write contention but requires periodic VACUUM to reclaim space from obsolete row versions. MVCC is why PostgreSQL can handle many concurrent users efficiently.

Related Terms

Write-Ahead Log (WAL)
A technique where changes are first written to a log before being applied to the database, ensuring crash recovery and data integrity.
Vacuum
A PostgreSQL maintenance operation that reclaims storage from dead tuples and updates statistics for the query planner.
NoSQL
A category of databases that store data in non-tabular formats, optimized for specific data models and access patterns.
Data Warehouse
A centralized repository optimized for analytical queries that integrates data from multiple operational sources.
Redis
An open-source, in-memory data store used as a database, cache, message broker, and queue with sub-millisecond response times.
Trigger
A database object that automatically executes a specified function when certain events (INSERT, UPDATE, DELETE) occur on a table.
 View All Databases Terms →