How to create a compound index in MongoDB through Java driver?

Question

I want to create compound index on `Age` and `Name` in MongoDB through Java driver and here is my syntax: ``` coll.ensureIndex(new BasicDBObject("Age", 1),new BasicDBObject("Name", -1)); List <DBObject> list = coll.getIndexInfo(); for (DBObject o : list) { System.out.println(o); } ``` but it create only 1 index not compund index and give me result this: ``` { "v" : 1 , "key" : { "_id" : 1} ,"ns" :"EmployeeData.EmpPersonalData", "name":"_id_"} { "v" : 1 , "key" : { "Age" : 1} , "ns" : "EmployeeData.EmpPersonalData" , "name" : "Age_1" , "Name" : -1} ``` So how can compund index on collection can be created through java driver?

Accepted Answer

If you look at your code, you have actually called `ensureIndex` with two parameters. Your first parameter was the key and your second parameter became some extra field: `Name: -1`.

What you are looking to pass in the first parameter is this object `{"Age":1, "Name":-1}`. What you actually passed was `{"Age":1}, {"Name":-1}`.

So you want to do something like this:

```
BasicDBObject obj = new BasicDBObject();
obj.put("Age", 1);
obj.put("Name", -1);
coll.ensureIndex(obj);
```

Note that the index will be created with a default name. To provide a specific name do the following:

```
coll.ensureIndex(obj, "MyName");
```

How to create a compound index in MongoDB through Java driver?

Solution

Problem