Repeatable Read and Serializable Isolation Levels (45 minutes)

Serializable and Repeatable Read isolation levels offer protections so your users won’t see weird or incorrect data – but there are tradeoffs for those protections.

Try the course quiz anytime.

In this course, you’ll dig into:

How to tell if your existing applications are using these types of isolation levels
When you might want to raise your isolation level in SQL Server
The tradeoffs you make if you choose serializable or repeatable read with disk based tables.

Note: In this course, we focus on disk-based tables. In-Memory OLTP (“Hekaton”) works differently — it’s not lock-based! Learn about In-Memory OLTP and Isolation Levels here.

Course scripts

https://github.com/LitKnd/SQLWorkbooks/tree/main/repeatable_read_and_serializable_isolation_levels

Each video in this course has English captions available, as well as a transcript below the video.

Lessons

Why do we have repeatable read and serializable? (10 minutes)

Demo: Give me correct data or give me death (15 minutes)

Animated diagram of the index intersection problem (6 minutes)

How you can get serializable isolation when you did not ask for it (4 minutes)

How to tell if apps are using repeatable read or serializable (5 minutes)

What is the best way to get correct data? (7 minutes)

Quiz on repeatable read & serializable isolation levels

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