I’m assuming SRC_SYSTEM is a field in your solr document. If so, you should be able to get a count of documents for each value of that field pretty easy with facets. Something like:
http://localhost:8983/solr/#/documents/query?q=:&q.op=OR&indent=true&facet=true&facet.field=SOURCE&rows=0&facet.limit=1000000
(That’s for SOURCE instead of SRC_SYSTEM.) Specifically, add the query parameters
facet=true
facet.field=SRC_SYSTEM
facet.limit=10000000
rows=0
The first three configure counting by the values of a field, indicated by the facet.field query parameter. The facet limit should just be set very high. It’s the number of field values to include in the response. Set rows to zero to not return any documents in the search. You can add filters/searches as normal, using &fq or &q, using the normal syntax, so you can look at the distribution of documents indexed within the last day (to check the last ETL job for instance).
The Solr interface allows you to do this pretty easy. Simply check facet at the bottom of the query panel on the left, which will open up more input boxes. Add the field name to facet.field and set the facet.limit as well. Setting rows to zero is done above below the sort field and above the fl field. (It’s the second box on the line between those two. The line is labeled “start, rows”.)
The response should have something like the below in it:
"facet_counts":{
"facet_queries":{},
"facet_fields":{
"SOURCE":[
"source2",159548,
"source1",158832,
"source4",158767,
"source3",158682,
"source5",32]},
"facet_ranges":{},
"facet_intervals":{},
"facet_heatmaps":{}}}
Meaning, there are about 160k documents that contain the value “source2” for the SOURCE field, “source1” has 159k, etc.
Let me know if this didn’t answer your question.