Hopefully a different take on an old question...
I'm wondering if there's a known formula for choosing when to have many indexes with, say, one shard each vs. one index with many shards, or some point in between, for the case where it's trivial to determine which node/shard on which to index/query data (i.e., it's chunkable).
Specifically, my data is routed via a (spatial + data type) hash, which is easy to divide across indexes and/or shards.
Is there any technical advantage/disadvantage to, say, 1-index-64-shards vs. 64-indexes-1-shard? AFAIK, increasing the node count would auto redistribute the shards either way.
This would include scaling, memory, and performance considerations.