Count in other index based on Current Index field

Elastic Stack Elasticsearch
5

Hello Mark, Thanks for your time. In simple terms, I just used, your Above code and got

"reason" : {
          "type" : "circuit_breaking_exception",
          "reason" : "[parent] Data too large, data for [<reused_arrays>] would be [19233470920/17.9gb], which is larger than the limit of [16238008729/15.1gb], real usage: [12220742088/11.3gb], new bytes reserved: [7012728832/6.5gb], usages [request=7042945328/6.5gb, fielddata=30858/30.1kb, in_flight_requests=1736/1.6kb, accounting=331419640/316mb]",
          "bytes_wanted" : 19233470920,
          "bytes_limit" : 16238008729,
          "durability" : "TRANSIENT"}

I think, I'm overloading the computation. But not sure, as I don't want to crash the server. Your suggestion would be helpful.