If you want to "delete by query" but you don't care about the atomicity of the "delete by query" (ie: queries and or other updates may process in the middle of the delete) then that is exactly what the delete() streaming expression decorator was designed for...
https://solr.apache.org/guide/solr/latest/query-guide/stream-decorator-reference.html#delete -Hoss http://www.lucidworks.com/
