MongoDB (2)-index creation

In the shell, look at the index that already exists in the collection, and you can run:

Db.things.getIndexes ()

To view all indexes in a database, you can run:

Db.system.indexes.find ()

Create an index

Db.things.ensureIndex ({j:1});

Build Options

The second parameter of the ENSUREINDEX function is the document/object that carries the creation option. These options are:

Options	Value	Default value
Background	True/false	False
Dropdups	True/false	False
Unique	True/false	False
Sparse	True/false	False
V	The index version. 0= earlier than v2.0 version, 1 = smaller/faster (current)	1 in v2.0.1 is used by default except in special situations

http://blog.csdn.net/xinghebuluo/article/details/7221639

Http://www.cnblogs.com/stephen-liu74/archive/2012/08/01/2561557.html

MongoDB (2)-index creation