ElasticSearch cheat sheet
Deleting and entire index is cheaper than updating (deleting documents) on existing index.
When searches must be limited to a certain user, route all the documents for that user to the same shard(use same shard key for all index, ex: userId).
When batch (re-)indexing, turn off refresh and enable after finished.
When you are sure that you don’t need to sort or aggregate on a field, or access the field value from a script, you can disable doc values in order to save disk space.