I had recently some discussions about auto resharding capabilities in Elasticsearch: basically, at some point in time, without any human intervention, the system would "detect" that for a given index resharding is needed in order to improve the performance.
I know that currently this mechanism is not supported and that elasticsearch provides some APIs to shrink or split the existing index. Even if ES does not support incremental resharding, the split capability could be used as a basis to build an auto resharding capability.
I have actually 2 questions:
do you think this resharding capability could be safely implemented? Resharding, usually requires to reindex the data. So it's a pretty expensive action that has a performance impact on the whole cluster. I suppose the split operation is much less expensive. Additionally, I suppose it can be hard to detect when a resharding operation would have a significant performance impact. So is it an operation that would be a good candidate for automation?
Since it's not provided by any Elasticsearch SaaS offering provider, are you aware of some teams who have successfully implemented it?