K.9 Order and Limit Data

Order and Limit Data with Cloud Firestore

Cloud Firestore provides powerful query functionality for specifying which documents you want to retrieve from a collection. These queries can also be used with either read() or addSnapshotListener(), as described in Get Data.

Order and limit data

Cloud Firestore also lets you specify the sort order for your data and specify a limit to how many documents you want to retrieve using orderBy() and limit(). For example, you could query for the first 3 cities alphabetically with:

citiesRef.orderBy("name").limit(3);

You could also sort in descending order to get the last 3 cities:

citiesRef.orderBy("name", Query.DESCENDING).limit(3);

You can also order by multiple fields. For example, if you wanted to order by state, and within each state order by population in descending order:

citiesRef.orderBy("state").orderBy("population", Query.DESCENDING);

You can combine where() filters with orderBy() and limit(). In the following example, the queries define a population threshold, sort by population in ascending order, and return only the first few results that exceed the threshold:

citiesRef.whereGreaterThan("population", 100000).orderBy("population").limit(2);

To learn more about valid and invalid limit/order queries, read here.