https://www.elastic.co/guide/en/elasticsearch/reference/master/removal-of-types.html
The above document clearly states that types are being removed because multiple types could lead to sparse data when they have few or no fields in common. This degrades the performance of elasticsearch.
My question is why do we then allow nested types and parent-child relationships in documents ? It looks like these two features will also create the same issues as the multiple mapping types. I would like to understand if this is true ?