MongoDB, Postgres, Microsoft SQL Server, or MySQL, or any other database manages concurrency control differently. There are two methods, pessimistic and optimistic, both have their pros and cons. Let explore how different databases implement this and what is the effect on performance/scalability.

This is often known as Optimistic vs pessimistic locking. Although I don't really like to use locking with this because it confuses the story.

0:00 Intro

2:20 What is Concurrency Control

6:00 Pessimistic Concurrency Control

14:50 Optimistic Concurrency Control

Resources

https://www.postgresql.org/docs/13/mvcc.html

http://source.wiredtiger.com/develop/architecture.html

https://docs.microsoft.com/en-us/troubleshoot/sql/performance/resolve-blocking-problems-caused-lock-escalation

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