I'm using GAE Datastore composite index and successfully created composite index 2 days ago. The index is in "serving" state. However the index is not automatically updated for new entries. Do I have to wait for it to be updated automatically, or I have to manually trigger with gcloud preview datastore create-indexes INDEX_FILE [GLOBAL-FLAG …] command? Thanks.
The entities will be automatically indexed, there is no need to manual create/run anything once you have created the composite index.
Note: The individual properties in the entity cannot be flagged as 'unindexed' if you want them in the composite index. This is because composite indexes require the individual property to be indexed as well.