Change record status: 
Project: 
Introduced in branch: 
11.4.x
Introduced in version: 
11.4.0
Description: 

A method to get all keys in a KeyValue collection, getAllKeys(), has been added to \Drupal\Core\KeyValueStore\KeyValueStoreInterface.

This method lets you know the keys of the items in a given collection without the need of loading all those items. This can help to reduce memory usage where a collection has a large number of items or when the items themselves are large.

Impacts: 
Module developers