How do I design Realtime Database in Firebase to scale?

Question

They provide the example below in the Firebase documentation for data organization. What happens when there are eventually 10,000 users signed up, but I decide to add another group? You'd have to write something to add the group with every existing user attached to that group as well as add every existing user to the new group entry? Is that right?

// An index to track Ada's memberships
{
  "users": {
  "alovelace": {
  "name": "Ada Lovelace",
  // Index Ada's groups in her profile
  "groups": {
     // the value here doesn't matter, just that the key exists
     "techpioneers": true,
     "womentechmakers": true
  }
},
...
},
"groups": {
  "techpioneers": {
    "name": "Historical Tech Pioneers",
    "members": {
      "alovelace": true,
      "ghopper": true,
      "eclarke": true
    }  
},
...

I'm building a little game with React-Native and using Realtime Database in Firebase for my database. I am building a customize section, where a user can purchase to unlock more customizations. If they purchase an item, it will set effect/{purchasedId}/members/{uid}/({isPurchased:true}) which will then display in my CustomizedSection with getCustomizablesForUserByUserId.

If I want to add more effects down the line, will I just have to add a new effect and attach every members ID to it?

Thanks!

Answer 1

What happens when there are eventually 10,000 users signed up, but I decide to add another group? You'd have to write something to add the group with every existing user attached to that group as well as add every existing user to the new group entry? Is that right?

That is indeed correct. This process is known as backfilling, and is a normal (and sometimes quite large) concern when using schemaless NoSQL databases.