Limit (Transformation Stage)

Description

Limits the number of documents returned by the pipeline.

Examples

Web

 const 
  
 pipeline 
  
 = 
  
 db 
 . 
 pipeline 
 () 
  
 // Step 1: Start a query with collection scope 
  
 . 
 collection 
 ( 
 "cities" 
 ) 
  
 // Step 2: Filter the collection 
  
 . 
 where 
 ( 
 field 
 ( 
 "population" 
 ). 
 greaterThan 
 ( 
 100000 
 )) 
  
 // Step 3: Sort the remaining documents 
  
 . 
 sort 
 ( 
 field 
 ( 
 "name" 
 ). 
 ascending 
 ()) 
  
 // Step 4: Return the top 10. Note applying the limit earlier in the 
  
 // pipeline would have unintentional results. 
  
 . 
 limit 
 ( 
 10 
 ); 
   test 
 . 
 firestore 
 . 
 js

Swift

 let 
  
 pipeline 
  
 = 
  
 db 
 . 
 pipeline 
 () 
  
 // Step 1: Start a query with collection scope 
  
 . 
 collection 
 ( 
 "cities" 
 ) 
  
 // Step 2: Filter the collection 
  
 . 
 where 
 ( 
 Field 
 ( 
 "population" 
 ). 
 greaterThan 
 ( 
 100000 
 )) 
  
 // Step 3: Sort the remaining documents 
  
 . 
 sort 
 ([ 
 Field 
 ( 
 "name" 
 ). 
 ascending 
 ()]) 
  
 // Step 4: Return the top 10. Note applying the limit earlier in the pipeline would have 
  
 // unintentional results. 
  
 . 
 limit 
 ( 
 10 
 ) 
   PipelineSnippets 
 . 
 swift

Kotlin
Android

 val 
  
 pipeline 
  
 = 
  
 db 
 . 
 pipeline 
 () 
  
 // Step 1: Start a query with collection scope 
  
 . 
 collection 
 ( 
 "cities" 
 ) 
  
 // Step 2: Filter the collection 
  
 . 
 where 
 ( 
 field 
 ( 
 "population" 
 ). 
 greaterThan 
 ( 
 100000 
 )) 
  
 // Step 3: Sort the remaining documents 
  
 . 
 sort 
 ( 
 field 
 ( 
 "name" 
 ). 
 ascending 
 ()) 
  
 // Step 4: Return the top 10. Note applying the limit earlier in the pipeline would have 
  
 // unintentional results. 
  
 . 
 limit 
 ( 
 10 
 ) 
   DocSnippets 
 . 
 kt

Java
Android

 Pipeline 
  
 pipeline 
  
 = 
  
 db 
 . 
 pipeline 
 () 
  
 // Step 1: Start a query with collection scope 
  
 . 
 collection 
 ( 
 "cities" 
 ) 
  
 // Step 2: Filter the collection 
  
 . 
 where 
 ( 
 field 
 ( 
 "population" 
 ). 
 greaterThan 
 ( 
 100000 
 )) 
  
 // Step 3: Sort the remaining documents 
  
 . 
 sort 
 ( 
 field 
 ( 
 "name" 
 ). 
 ascending 
 ()) 
  
 // Step 4: Return the top 10. Note applying the limit earlier in the pipeline would have 
  
 // unintentional results. 
  
 . 
 limit 
 ( 
 10 
 ); 
   DocSnippets 
 . 
 java

Python

 from 
  
 google.cloud.firestore_v1.pipeline_expressions 
  
 import 
 Field 
 pipeline 
 = 
 ( 
 client 
 . 
 pipeline 
 () 
 . 
 collection 
 ( 
 "cities" 
 ) 
 . 
 where 
 ( 
 Field 
 . 
 of 
 ( 
 "population" 
 ) 
 . 
 greater_than 
 ( 
 100_000 
 )) 
 . 
 sort 
 ( 
 Field 
 . 
 of 
 ( 
 "name" 
 ) 
 . 
 ascending 
 ()) 
 . 
 limit 
 ( 
 10 
 ) 
 ) 
   firestore_pipelines 
 . 
 py

Java

 Pipeline 
  
 pipeline 
  
 = 
  
 firestore 
  
 . 
 pipeline 
 () 
  
 . 
 collection 
 ( 
 "cities" 
 ) 
  
 . 
 where 
 ( 
 field 
 ( 
 "population" 
 ). 
 greaterThan 
 ( 
 100_000 
 )) 
  
 . 
 sort 
 ( 
 ascending 
 ( 
 field 
 ( 
 "name" 
 ))) 
  
 . 
 limit 
 ( 
 10 
 ); 
   PipelineSnippets 
 . 
 java

Behavior

The limit(...) stage will only return the first N documents. Unless a sort(...) stage is used before the limit, the order in which documents are returned is unstable and repeated executions may produce different results.