I’m studying Cache Read strategies.

I found two strategies are generally used.

• Look-Aside strategy.
• Read-Through strategy.

I understood difference of Look-Aside and Read-Through is “Who has Responsibility for Caching”.

Many articles are saying

A: “If use Read-Through strategy, Data consistency problems can be avoided by always synchronizing data between cache and DB.”

and

B: “With the Read-Through strategy, you will always get a cache miss the first time you request data.”

But, I can’t understand A and B.
I have two question.

• Q1: In A, If there is data in the cache, it is returned as is. How can data consistency be guaranteed?

• Q2: In B, Even with the Look-Aside strategy, doesn’t a cache miss occur when data is first requested?

I looked up cache writing strategies.

In this process, I understood the Write Back strategy, Write Through strategy, and Write Around strategy.