This is material where I personally jot down things I don't know and briefly organize what I come to learn. If you know something among the unanswered questions, please leave a comment. Thank you.
Full Q&A List
[Answered]
1. What is @CacheKeyMethod?
It is an SSM-related annotation and a method that provides the key value; if there is none, it calls toString(). Additionally, if the namespace within the cache uses toString() and the same key exists, a collision occurs.
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2. Why should we cache DB data?
There is an issue where fetching data from the DB every time is very slow.
Reference