I have millions of metrics for ~1 hundred sources (the number of sources will raise in the future).
A query is always for a single source.
I'm already splitting the indices per day.
I'm trying to decide between multiple indices - one per source vs a single index with the source as a term in the document (in this case, all queries will use a term filter with the source id).
Is there a performance difference between the 2 above? during index? during query?
The cluster is write heavy- thousands of index requests (that translate to tens of bulk requests) per second.