==============
Create Indexes
==============

To create an index on a field or fields, pass an index specification
document to the ``createIndex()`` method:

.. code-block:: js


      { <field1>: <type1>, <field2>: <type2> ... }

Create an Ascending Index
-------------------------

For an ascending index type, specify ``1`` for ``<type>``.

The following example creates an ascending index key for the
``dateOfBirth`` field:

.. code-block:: js

   async function createAscendingIndex(db) {
     // Get the users collection
     const collection = db.collection('users');

     // Create the index
     const result = await collection.createIndex({ dateOfBirth : 1 });
     console.log(result);
     return result;
   };

Create a Descending Index
-------------------------

For an descending index type, specify ``-1`` for ``<type>``.

The following example specifies a descending index key on the
``lastName`` field:

.. code-block:: js

   async function createDescendingIndex(db) {
     // Get the documents collection
     const collection = db.collection('users');

     // Create the index
     const result = await collection.createIndex({ lastName : -1 });
     console.log(result);
     return result;
   };

Create a Compound Index
-----------------------

To specify a compound index, use the ``compoundIndex`` method.

The following example specifies a compound index key composed of the
``lastName`` field sorted in descending order, followed by the
``dateOfBirth`` field sorted in ascending order:

.. code-block:: js

   async function createCompoundIndex(db) {
     // Get the documents collection
     const collection = db.collection('users');

     // Create the index
     const result = await collection.createIndex({ lastName : -1, dateOfBirth : 1 });
     console.log(result);
     return result;
   };

Create a Text Index
-------------------

MongoDB also provides
:manual:`text </core/index-text/>` indexes to
support text search of string content. Text indexes can include any
field whose value is a string or an array of string elements.

This example specifies a text index key for the ``comments`` field:

.. code-block:: js

   async function createTextIndex(db) {
     // Get the documents collection
     const collection = db.collection('users');

     // Create the index
     const result = await collection.createIndex({ comments : "text" });
     console.log(result);
     return result;
   };

Create a Hashed Index
---------------------

To specify a :manual:`hashed </core/index-hashed/>` index key,
use the ``hashed`` method.

This example specifies a hashed index key for the ``timestamp`` field:

.. code-block:: js

   async function createHashedIndex(db) {
     // Get the documents collection
     const collection = db.collection('users');

     // Create the index
     const result = await collection.createIndex({ timestamp : "hashed" });
     console.log(result);
     return result;
   };

Create Geospatial Indexes
-------------------------

There are also helpers for creating the index keys for the various
geospatial indexes supported by mongodb.

Create a ``2dsphere`` Index
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

To specify a :manual:`2dsphere </core/2dsphere/>`
index key, use one of the ``geo2dsphere`` methods.

This example specifies a 2dsphere index on the ``location`` field:

.. code-block:: js

   async function create2dSphereIndex(db) {
     // Get the documents collection
     const collection = db.collection('users');

     // Create the index
     const result = await collection.createIndex({ location : "2dsphere" });
     console.log(result);
     return result;
   };

Create a ``2d`` Index
^^^^^^^^^^^^^^^^^^^^^^^^^

To specify a :manual:`2d </core/2d/>` index key, use the ``geo2d``
method.

.. important::

   A 2d index is for data stored as points on a two-dimensional plane
   and is intended for legacy coordinate pairs used in MongoDB 2.2 and
   earlier.


This example specifies a 2d index on the ``points`` field:

.. code-block:: js

   async function create2dIndex(db) {
     // Get the documents collection
     const collection = db.collection('users');

     // Create the index
     const result = await collection.createIndex({ points : "2d" });
     console.log(result);
     return result;
   };

IndexOptions
------------

In addition to the index specification document, ``createIndex``
method can take an index options document, such as to create unique
indexes or partial indexes.

Create a Unique Index
^^^^^^^^^^^^^^^^^^^^^

.. code-block:: js

   async function createUniqueIndex(db) {
     // Get the documents collection
     const collection = db.collection('users');

     // Create the index
     const result = await collection.createIndex(
       { lastName : -1, dateOfBirth : 1 },
       { unique:true }
     );
     console.log(result);
     return result;
   };

Create a Partial Index
^^^^^^^^^^^^^^^^^^^^^^

.. code-block:: js

   async function createPartialIndex(db) {
     // Get the documents collection
     const collection = db.collection('users');

     // Create the index
     const result = await collection.createIndex(
       { lastName : 1, firstName: 1 },
       { partialFilterExpression: { points: { $gt: 5 } }
     });
     console.log(result);
     return result;
   };

For other index options, see :manual:`Index Options </core/index-properties/>` .

createIndexes
-------------

The driver also supports the helper method ``createIndexes``. Unlike ``createIndex``, 
``createIndexes`` takes in raw index specifications:

.. code-block:: js

   async function createMultipleIndexes(db) {
     const collection = db.collection('users');
     await collection.createIndexes([
       // Simple index on field firstName
       {
         key: { firstName: 1 }
       },
       // wildcard index
       {
         key: { '$**': 1 }
       },
       // named index on lastName and firstName
       {
         key: { lastName: 1, firstName: -1 }
         name: 'lastNameReverseFirstName'
       }
     ]);
   });

You can find more info on raw index specifications :manual:`here </reference/command/createIndexes/>` .