.NET Architecture & System Design Interview Question #74

What is optimistic concurrency control?

Database Scaling, Partitioning, NoSQL & Data Consistency Mid-Level Intermediate

Quick Interview Answer

Optimistic concurrency control assumes conflicts are relatively uncommon. A record carries a version or concurrency token, and an update succeeds only if the version has not changed since it was read.

Detailed Explanation

If another writer changed the record first, the update detects a conflict and the application can retry, merge, or ask the user to resolve it. EF Core supports concurrency tokens such as SQL Server rowversion.

Code Example

UPDATE Orders
SET Status = @status
WHERE Id = @id
  AND Version = @originalVersion;

0 rows updated -> concurrency conflict