Job Counters Launched reduce tasks=45 Rack-localms)=200225 Total vcore-seconds taken by all reduceTotal megabyte-seconds taken by all map tasks=30042112
Total me
有人能描述一下这个操作的实际作用吗?据我所知,这是一张地图,但values和reduce到底是什么意思呢?据我所知,它把闭包作为一个参数,对吧?let result = self.myDictionary.values.reduce(0) { (count, objectInMyDictionary) in
return count据我所知,上面的方法将作为myDictionary中所有对象的迭代器。所以实际上我可以通过循环来做到这一点,我猜结果会是一样
当我调用mapReduce时db.my_collection.mapReduce(map, reduce,{})2019-12-11T09:58:05.492+0800 E QUERY [js]TypeError: c.out is undefined :
DBCollection.prototype.mapReduce@src