Second orderBy query does nothing in Firestore (react-native-firebase)

Question

EDIT So after reviewing this problem with firebase developer this is working by design and there is no actual way to acheive this. Offical response from firestore dev:

Admittedly certain kinds of queries are difficult, if not feasible, when working with Firestore's NoSQL design. If the lack of such capabilities is considered a deal-breaker for your use-case, then it's likely that Firestore may not be the right database solution for you.

If you're desperate to achieve something similar then possibly this solution will work for you: https://firebase.google.com/docs/firestore/solutions/arrays#solution_a_map_of_values.

If not there is always AWS

===========================================================================

I'm noticing that the second orderBy query option does nothing to the data that is returned. Consider the following query:

firebase.firestore()
  .collection('posts')
  .orderBy('date', 'desc')
  .where('date', '>', new Date(1529802276644))
  .orderBy('rating', 'desc')
  .limit(size)

This query is intending to order posts by the date field, then filter then for the last two days, then order them by rating.

This query is currently returning 3 posts within two days, however is not sorting by rating. The results I receive are:

[
  {date: 3 hours ago, rating: 1},
  {date: 5 hours ago, rating: -1},
  {date: 9 hours ago, rating: 0},
]

And if I conduct the same query with the last orderBy removed, I actually get the exact same results:

firebase.firestore()
  .collection('posts')
  .orderBy('date', 'desc')
  .where('date', '>', new Date(1529802276644))
  .limit(size)

produces:

[
  {date: 3 hours ago, rating: 1},
  {date: 5 hours ago, rating: -1},
  {date: 9 hours ago, rating: 0},
]

I currently have an enabled index over posts. I'm fairly certain the index is correct because I was previously getting an error about a missing index before this and then fixed it with this index:

posts |  date DESC rating DESC   |    enabled

I'm pretty sure the problem lies with firebase and not with the library I'm using react-native-firebase. The firebase firestore SDK I am using is on 5.0.4 I believe

EDIT Here is how I actually use the code within my react-native project:

const episodeRef = firebase.firestore().collection('posts');
const baseRequest = episodeRef.orderBy('date', 'desc').where('date', '>', new Date(1529802276644)).orderBy('rating', 'desc').limit(25)
const documentSnapshots = await baseRequest.get()
console.log('documentSnapshots', documentSnapshots);

The console.log prints out a valid querysnapshot, and the _query field roughly looks like this:

_fieldFilters:{
    fieldPath:{
        string:"date",
        type:"string"
    },
    operator:"GREATER_THAN",
    value:{
        type:"date",
        value:1529802276644
    },
}
_fieldOrders:{
    0:{
        direction:"DESCENDING",
        fieldPath: {
            string:"date",
            type:"string"
        },
    }
    1:{
        direction:"DESCENDING"
        fieldPath:{
            string:"rating",
            type:"string"
        }
    }
}

(bad printing due to copying)

Answer 1

I'm not certain this is the cause, but in Firebase Realtime Database it is a common mistake, so it's worth a short here too.

When you convert the QuerySnapshot documentSnapshots to a string, it loses any information on the order of the data.

Instead loop over the results with QuerySnapshot.forEach() to ensure you maintain the order you requested the data in:

const documentSnapshots = await baseRequest.get()
documentSnapshots.forEach(document => {
  console.log('document', document);
});

If that works, this probably also works:

const documentSnapshots = await baseRequest.get()
console.log('document', documentSnapshots.docs());