// https://jira.mongodb.org/browse/SERVER-4534 // Building an index in the foreground on a field with a large array and few documents in // the collection used to open too many files and crash the server. let t = db.huge_multikey_index; t.drop(); function doit() { let arr = []; for (var i = 0; i < 1000 * 1000; i++) arr.push(i); t.insert({a: arr}); // t.createIndex({a:1}, {background:true}) // always worked t.createIndex({a: 1}); // used to fail server with out of fds error } doit();