A database index is a data structure that improves the speed of data retrieval operations on a database table at the cost of additional writes and storage space to maintain the index data structure.
Let's connect to test collection and inspect how MongoDB processes a query
mongo testdb
db.movies.find({title: new RegExp("godfather", "i")}).explain()
Create index
db.movies.ensureIndex({title: 1})
We only need to create an index once for a single collection. After initial creation, MongoDB automatically updates the index as data changes.
To list a collection’s indexes, use the db.collection.getIndexes().
To check the sizes of the indexes on a collection, use db.collection.stats().
In MeteorJS you can set indexing in SimpleSchema (package meteor-collection2). Simple snippet in CoffeeScript
MovieSchema = new SimpleSchema
title:
type: String
label: "Title"
max: 250
index: 1
Set to 1 or true for an ascending index. Set to -1 for a descending index. Or you may set this to another type of specific MongoDB index, such as "2d". Indexes work on embedded sub-documents as well.
If you have created an index for a field by mistake and you want to remove or change it, set index to false.
Useful links