Due to error in client code, mongodb have created many \"mr.mapreduce....\" collections, how to remove them all (by mask maybe).
I run script in interactive shell:
function f() { var names = db.getCollectionNames(); for(var i = 0; i < names.length; i++){ if(names[i].indexOf("mr.") == 0){ db[names[i]].drop();}}}; f();
It resolved my problem.