The process of using Apollo Client from scratch and thinking of a better cache implementation.

1. When graphql doesn't need a cache.

Basically, it uses InMemoryCache in the first place, so by default it will be saved automatically.

const client = new ApolloClient({
  cache: new InMemoryCache({});
});

I have not used the so-called cache control methods such as readQuery, readFragment, etc. much.
In fact, I was at a loss to figure out how to use this method successfully in a case where my app needed rich data binding.

2. Initially

I achieved my goal by putting data into useReactive and then updating this data cleanly when it changed.

const cache = useReactive(userCache);

// Updated...
const updatedUser = ...
userCache(cache, { ...updatedUser } ); // It's hardest when it's nested.

However, it is a pain in the ass to change the data in this way. In the first place, there are so many times to change the data that it becomes a little difficult to handle. For example, graphql returns an array of data from related tables that are nested more than 5 layers deep, and it is stupid to change them honestly every time.

3. The next thing I thought of was refetch.

This is the most reliable method now, but the worst in terms of performance.

const { refetch } = useQuery(USER);

// Updated...
refetch().then();

As before, we no longer have to foolishly update the data, we only have to throw another query to bring the data up to date.

4. In the end

I settled on caching the data in the InMemoryCache on initial load, and refetching the data with cache-only when updating the data.

initial load

const { loading, data } = useQuery(USER, {
  fetchPolicy: 'no-cache',
});

updated

const { refetch } = useQuery(USER, {
  fetchPolicy: 'cache-only',
});

// Updated...
refetch().then();

I don't know what approach I will change to in the future, as I am still working on Apollo currently. I'm still learning every day.
To be honest, I know that I should study the Fragment area properly, but I haven't been able to do so yet.

I'm happy to say that I've managed to avoid the worst case scenario of data inconsistency.

Finally

If anyone reading this knows of a better caching strategy for the Apollo Client, a good document (other than the official one), or an easy way to do it, I would be very happy to hear about it.