Hi Pramod,
There might be other ways to do this, but I found a way to get those counts only for specific indexes (not wildcarded);
I have packetbeat and topbeat running. I created an index pattern *beat-* which is what I've used in this Data Table visualization. I Split Rows on a Filters aggregation type, and added 2 filters;
_index: topbeat-2016.08.24
and
_index: packetbeat-2016.08.24
Regards,
Lee
Also see https://www.elastic.co/guide/en/elasticsearch/reference/current/mapping-index-field.html
which describes that _index is a virtual field. It's not something that is an actual indexed field in the docs.