MongoDB remove mapreduce collection

Question

Due to error in client code, mongodb have created many \"mr.mapreduce....\" collections, how to remove them all (by mask maybe).

Answer 1

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.

Answer 2

Temporary map-reduce table should be cleaned up when the connection which created them is closed:

map/reduce is invoked via a database command. The database creates a temporary collection to hold output of the operation. The collection is cleaned up when the client connection closes, or when explicitly dropped. Alternatively, one can specify a permanent output collection name. map and reduce functions are written in JavaScript and execute on the server.

-- MongoDB docs

If not, you could delete them using them same method you would delete any other collection. It might get a bit repetitive though.