Order and limit data
Firestore provides powerful query functionality for specifying which
documents you want to retrieve from a collection. These queries can also be used
with either get()
or addSnapshotListener()
, as described in Get
Data.
Order and limit data
By default, a query retrieves all documents that satisfy the query in ascending
order by document ID. You can specify the sort order for your data using
orderBy()
, and you can limit the number of documents retrieved using
limit()
. If you specify a limit()
, the value must be greater than or equal
to zero.
For example, you could query for the first 3 cities alphabetically with:
Web version 9
import { query, orderBy, limit } from "firebase/firestore"; const q = query(citiesRef, orderBy("name"), limit(3));
Web version 8
citiesRef.orderBy("name").limit(3);
Swift
citiesRef.order(by: "name").limit(to: 3)
Objective-C
[[citiesRef queryOrderedByField:@"name"] queryLimitedTo:3];
Kotlin+KTX
Android
citiesRef.orderBy("name").limit(3)
Java
Android
citiesRef.orderBy("name").limit(3);
Dart
final citiesRef = db.collection("cities"); citiesRef.orderBy("name").limit(3);
Java
Python
Python
(Async)
C++
cities_ref.OrderBy("name").Limit(3);
Node.js
Go
PHP
PHP
To authenticate to Firestore, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.
Unity
Query query = citiesRef.OrderBy("Name").Limit(3);
C#
Ruby
You could also sort in descending order to get the last 3 cities:
Web version 9
import { query, orderBy, limit } from "firebase/firestore"; const q = query(citiesRef, orderBy("name", "desc"), limit(3));
Web version 8
citiesRef.orderBy("name", "desc").limit(3);
Swift
citiesRef.order(by: "name", descending: true).limit(to: 3)
Objective-C
[[citiesRef queryOrderedByField:@"name" descending:YES] queryLimitedTo:3];
Kotlin+KTX
Android
citiesRef.orderBy("name", Query.Direction.DESCENDING).limit(3)
Java
Android
citiesRef.orderBy("name", Direction.DESCENDING).limit(3);
Dart
final citiesRef = db.collection("cities"); citiesRef.orderBy("name", descending: true).limit(3);
Java
Python
Python
(Async)
C++
cities_ref.OrderBy("name", Query::Direction::kDescending).Limit(3);
Node.js
Go
PHP
PHP
To authenticate to Firestore, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.
Unity
Query query = citiesRef.OrderByDescending("Name").Limit(3);
C#
Ruby
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:
Web version 9
import { query, orderBy } from "firebase/firestore"; const q = query(citiesRef, orderBy("state"), orderBy("population", "desc"));
Web version 8
citiesRef.orderBy("state").orderBy("population", "desc");
Swift
citiesRef .order(by: "state") .order(by: "population", descending: true)
Objective-C
[[citiesRef queryOrderedByField:@"state"] queryOrderedByField:@"population" descending:YES];
Kotlin+KTX
Android
citiesRef.orderBy("state").orderBy("population", Query.Direction.DESCENDING)
Java
Android
citiesRef.orderBy("state").orderBy("population", Direction.DESCENDING);
Dart
final citiesRef = db.collection("cities"); citiesRef.orderBy("state").orderBy("population", descending: true);
Java
Python
Python
(Async)
C++
cities_ref.OrderBy("state").OrderBy("name", Query::Direction::kDescending);
Node.js
Go
PHP
PHP
To authenticate to Firestore, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.
Unity
Query query = citiesRef.OrderBy("State").OrderByDescending("Population");
C#
Ruby
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:
Web version 9
import { query, where, orderBy, limit } from "firebase/firestore"; const q = query(citiesRef, where("population", ">", 100000), orderBy("population"), limit(2));
Web version 8
citiesRef.where("population", ">", 100000).orderBy("population").limit(2);
Swift
citiesRef .whereField("population", isGreaterThan: 100000) .order(by: "population") .limit(to: 2)
Objective-C
[[[citiesRef queryWhereField:@"population" isGreaterThan:@100000] queryOrderedByField:@"population"] queryLimitedTo:2];
Kotlin+KTX
Android
citiesRef.whereGreaterThan("population", 100000).orderBy("population").limit(2)
Java
Android
citiesRef.whereGreaterThan("population", 100000).orderBy("population").limit(2);
Dart
final citiesRef = db.collection("cities"); citiesRef .where("population", isGreaterThan: 100000) .orderBy("population") .limit(2);
Java
Python
Python
(Async)
C++
cities_ref.WhereGreaterThan("population", FieldValue::Integer(100000)) .OrderBy("population") .Limit(2);
Node.js
Go
PHP
PHP
To authenticate to Firestore, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.
Unity
Query query = citiesRef .WhereGreaterThan("Population", 2500000) .OrderBy("Population") .Limit(2);
C#
Ruby
However, if you have a filter with a range comparison (<
, <=
, >
, >=
),
your first ordering must be on the same field, see the list of orderBy()
limitations below.
Limitations
Note the following restriction for orderBy()
clauses:
- An
orderBy()
clause also filters for existence of the given fields. The result set will not include documents that do not contain the given fields.
orderBy
and existence
When you order a query by a given field, the query can return only the documents where the order-by field exists.
For example, the following query would not return any documents where the
population
field is not set, even if they otherwise meet the query filters.
Java
db.collection("cities").whereEqualTo("country", “USA”).orderBy(“population”);
A related effect applies to inequalities. A query with an inequality filter
on a field also implies ordering by that field. The following
query does not return documents without a population
field even
if country = USA
in that document . As a workaround, you can execute
separate queries for each ordering or you can assign a value for all fields
that you order by.
Java
db.collection(“cities”).where(or(“country”, USA”), greaterThan(“population”, 250000));
The query above includes an implied order-by on the inequality and is equivalent to the following:
Java
db.collection(“cities”).where(or(“country”, USA”), greaterThan(“population”, 250000)).orderBy(“population”);