Good spring festival running, and database "read/write separation" considerations

Good spring festival running, and database "read/write separation" considerations

Good Spring Festival;
Small wind blowing;
The same flower taste;
Full of happiness.

It's a wonderful thing to keep running on the spacious road.

Running is always boring, only running;
Running is lonely, and everyone has their own pace;

I was always confused when I was running. Yesterday I talked to some students about the database "read/write splitting ".
In my limited understanding, I always think that the database "read/write splitting" is to improve the bottleneck of the database, because the database write is always relatively small, and the read may always be relatively large, even several orders of magnitude.
For example, an e-commerce website may only need to write a product once a month, but there are 10 thousand views every day. At this time, "read/write splitting" occurs ", I think it is the most appropriate.
However, some people tell me mysteriously that the most important goal of "read/write splitting" is to make the system more fault tolerant and ensure that when the database responsible for writing fails, the whole system is still running. At that time, I thought this idea was very good and awesome!

When I was running, I suddenly thought that using fault tolerance to understand "read/write splitting" is a good method. But fault tolerance should be more appropriate;
For example, the RAC mode of the ORACLE database. if the system is very important, we can set the RAC databases with Four heartbeat nodes and place them in different data centers or regions.

I am not a smart or wise person. I think a lot of things are really slow. I can only think about it slowly, so I can only be an ordinary person.