索引能提高檢索數(shù)據(jù)的速度，你可以想像成在MySQL中創(chuàng)建索引一樣，同樣索引也是用B-Tree也實現(xiàn)的。

創(chuàng)建schedule的collection：

// 實例化Mongo對象，連接27017端口

Mongo mongo = new Mongo("localhost", 27017);

// 連接名為yourdb的數(shù)據(jù)庫，假如數(shù)據(jù)庫不存在的話，mongodb會自動建立

DB db = mongo.getDB("test");

//得到要查詢數(shù)據(jù)的 Collction, 如果沒有就創(chuàng)建

DBCollection coll = db.getCollection("schedule");

Getting a List of Indexes on a Collection

Creating An Index

創(chuàng)建索引

MongoDB supports indexes, and they are very easy to add on a collection. To create an index, you just specify the field that should be indexed, and specify if you want the index to be ascending (1) or descending (-1). The following creates an ascending index on the "i" field :

MongoDB支持索引，并且很容易添加。只需要指定索引的字段和排序（升序1，降序-1）。下面是創(chuàng)建i降序索引的例子：

Getting a List of Indexes on a Collection

查詢collection全部索引

You can get a list of the indexes on a collection :

and you should see something like

打印如下