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.