var coll = db.getSiblingDB('createindexes').validandinvalid; coll.drop(); // the second index spec is invalid because it's missing a 'key' field var indexes = [{key: {foo: 1}, name: 'first'}, {name: 'second'}]; // attempt to create the indexes var res = coll.runCommand('createIndexes', {indexes: indexes}); printjson(res); // the first index was created (along with an _id index) printjson(coll.getIndexes()) // the result document is missing a numIndexesAfter field even though // an index was added assert.eq(res.hasOwnProperty('numIndexesAfter'), true);