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+++
date = "2015-03-17T15:36:56Z"
title = "Create Indexes"
[menu.main]
parent = "Tutorials"
identifier = "Create Indexes"
weight = 35
pre = "<i class='fa'></i>"
+++
# Create Indexes
To create an index on a field or fields, pass an index specification
document to the `createIndex()` method:
```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:
```js
function createAscendingIndex(db, callback) {
// Get the users collection
const collection = db.collection('users');
// Create the index
collection.createIndex(
{ dateOfBirth : 1 }, function(err, result) {
console.log(result);
callback(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:
```js
function createDescendingIndex(db, callback) {
// Get the documents collection
const collection = db.collection('users');
// Create the index
collection.createIndex(
{ lastName : -1 }, function(err, result) {
console.log(result);
callback(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:
```js
function createCompoundIndex(db, callback) {
// Get the documents collection
const collection = db.collection('users');
// Create the index
collection.createIndex(
{ lastName : -1, dateOfBirth : 1 }, function(err, result) {
console.log(result);
callback(result);
});
};
```
## Create a Text Index
MongoDB also provides
[text](https://docs.mongodb.org/manual/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:
```js
{{% create-text-index %}}
```
## Create a Hashed Index
To specify a [hashed](https://docs.mongodb.org/manual/core/index-hashed/) index key,
use the ``hashed`` method.
This example specifies a hashed index key for the ``timestamp`` field:
```js
function createHashedIndex(db, callback) {
// Get the documents collection
const collection = db.collection('users');
// Create the index
collection.createIndex(
{ timestamp : "hashed" }, function(err, result) {
console.log(result);
callback(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 [2dsphere](https://docs.mongodb.org/manual/core/2dsphere/)
index key, use one of the ``geo2dsphere`` methods.
This example specifies a 2dsphere index on the ``location`` field:
```js
{{% create-2dsphere-index %}}
```
### Create a `2d` Index
To specify a [2d](https://docs.mongodb.org/manual/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:
```js
function create2dIndex(db, callback) {
// Get the documents collection
const collection = db.collection('users');
// Create the index
collection.createIndex(
{ points : "2d" }, function(err, result) {
console.log(result);
callback(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
```js
function createUniqueIndex(db, callback) {
// Get the documents collection
const collection = db.collection('users');
// Create the index
collection.createIndex(
{ lastName : -1, dateOfBirth : 1 },
{ unique:true },
function(err, result) {
console.log(result);
callback(result);
});
};
```
### Create a Partial Index
```js
function createPartialIndex(db, callback) {
// Get the documents collection
const collection = db.collection('users');
// Create the index
collection.createIndex(
{ lastName : 1, firstName: 1 },
{ partialFilterExpression: { points: { $gt: 5 } } },
function(err, result) {
console.log(result);
callback(result);
});
};
```
For other index options, see [Index Options](https://docs.mongodb.org/manual/core/index-properties/).
|
