创建索引

索引能提高检索数据的速度，你可以想像成在MySQL中创建索引一样，同样索引也是用B-Tree也实现的。

创建schedule的collection：

// 实例化Mongo对象，连接27017端口

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

// 连接名为yourdb的数据库，假如数据库不存在的话，mongodb会自动建立

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

//得到要查询数据的 Collction, 如果没有就创建

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

Getting a List of Indexes on a Collection

List<DBObject> indexList = coll.getIndexInfo();  

for (DBObject o : indexList) {  

        System.out.println("index ---------" + o);  

}

Creating An Index

创建索引

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）。下面是创建i降序索引的例子：

view source

print?

1	coll.createIndex(new BasicDBObject("i", 1));  // create index on "i", ascending

 

Getting a List of Indexes on a Collection

查询collection全部索引

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

 

1	List<DBObject> list = coll.getIndexInfo();

2

3

4

5	for (DBObject o : list) {

6

7	System.out.println(o);

8

9

}

 

and you should see something like

打印如下

1	{ "name" : "i_1" , "ns" : "mydb.testCollection" , "key" : { "i" : 1} }