Parent-child performance issue

[xam]

Thank you for your answer,

@mvg

Did you configure eager global ordinals loading on the _parent field?

If I understand well, if I move to eager global ordinals loading, it will only speed up the first parent/child query? Am I right?

@mvg

This is the worst possible scenario for the has_child query. If you have other queries next to the has_child query the response time should be much faster. The join will only be computed for documents that match with the other queries.

Good to know, thank you. I will try to analyze if my queries are closed to the worst case or not.

@mvg

Parent/child in Elasticsearch scales well. So if the performance is not what you want it to be then you can always increase the number of primary shards (and reindex (from 2.3 their is a reindex api)) and add more nodes.

I think I know the answer, but can I expect best performance with more shards, without adding more nodes? What is the limiting hardware for parent/child query processing? Is there a way to see what is the bottleneck on the hardware point of view?

Thank you,