1. Typo in lecture materials - There are often typos in some parts of the lecture materials (PDF). [Errata] (1) Chapter 04-5 (14p) - Depending on the scope of use --> Depending on the scope of use (2) Chapter 05 (16p) - Data persistence is not guaranteed --> Data persistence is not guaranteed. 2. Lack of graphic materials - In the Redis Sync chapter, it would be nice to explain the process with several pictures. - Most of it was explained in words, so it was difficult to understand intuitively. 3. No simple example code included - It's something you can find by googling, but it would be nice to include example code for CRUD by Value type. I give 4 points because it was very helpful to explain the parts where Redis can fail (keys command, Thundering Herd).