javascript - In Firestore, how can you do a compound query involving a key in a map without creating an index for every key?

Question

In Firestore, how can you do a compound query involving a key in a map without creating an index for every key?

For example, consider a collection which holds blog posts, and each blog post has categories.

Post {
    title: ..
    ...
    categories: {
        cats: true
        puppies: true
    }   
}

In order to query posts in a particular category in a paginated way, we would do something like this:

let query = db.collection(`/posts`)
    .where(`categories.${categoryId}`, '==', true)
    .orderBy('createdAt')
    .startAfter(lastDate)
    .limit(5);

But it seems that this would require a composite index (categories.<categoryId> and createdAt) for every single category. Is there any way around this?

In my case, it isn't feasible to create composite indices for every category since categories are user-generated, and could easily exceed 200 (the limit for composite indices in Firestore).

Answer 1

Waitting for answers