using ensureIndex in mongodb schema using mongoose

Question

I would like to call ensureIndex on the authorName, what is the command and where in this code should I put it?

var mongoose = require('mongoose');

// defines the database schema for this object
var schema = mongoose.Schema({
    projectName : String,
    authorName : String,
    comment : [{
        id : String,                                    
        authorName : String,
        authorEmailAddress : { type : String, index : true }    
    }]
});

// Sets the schema for model
var ProjectModel = mongoose.model('Project', schema);

// Create a project
exports.create = function (projectJSON) {
    var project = new ProjectModel({
        projectName : projectJSON.projectName,
        authorName : projectJSON.authorName,    

        comment : [{
            id : projectJSON.comments.id,                                           
            authorName : projectJSON.comments.authorName,                           
            authorEmailAddress : projectJSON.authorEmailAddress
        });

        project.save(function(err) {
            if (err) {
                console.log(err);
            } else{
                console.log("success");
            }
        });
    });
}

Solution 1

You don't call ensureIndex directly, you indicate that field should be indexed in your schema like this:

var schema = mongoose.Schema({
  projectName : String,
  authorName : { type: String, index: true }
});

Based on that definition, Mongoose will call ensureIndex for you when you register the model via the mongoose.model call.

To see the ensureIndex calls that Mongoose is making, enable debug output by adding the following to your code:

mongoose.set('debug', true);

Solution 2

You could use this statement:

mongoose.connection.collections['my_collection'].ensureIndex({ "key": 1 }, { "unique": true }, callback);

For example you want to do some integration tests, so you will need to drop your collections rapidly. In that case mongoose doesn't setup indexes again during runtime even if option autoIndex is set to true. This answer could be useful in that case.

Solution 3

you can call Schema#index method to create index

let urlSchema = new Schema({
    url: String,
    status: Number
  }
);
urlSchema.index({ url: 1 }, { unique: true, background: true, dropDups: true });

you can listen createing index event.

let UrlModel = mongoose.model('url', urlSchema);
UrlModel.on('index', function(error) {
  if (error && error.message) {
    console.log(`Url collection create index error:${error.message}`);
  }
});

Note: the process of creating index is asynchronous.so when you create unique index,you cannot insert duplicate data. or creating index will fail;

Solution 4

First define index on authorName field and if you manually want invoke ensureIndex because of certain requirement then you have to set autoIndex to false. This is what your schema would look like:

var schema = mongoose.Schema({
    projectName : String,
    authorName : {type : String, index : true}
    comment : [{
        id : String,                                    
        authorName : String,
        authorEmailAddress : { type : String, index : true }    
    }]
}, {
     // Turn-off auto indexing, we manually need to trigger indexing 
     autoIndex : false 
});

And based on the requirement you can invoke ensureIndexes method on the model that you have created using this schema i.e. ProjectModel.ensureIndexes();

View more solutions

Comments

[bouncingHippo]

will having many indexes be a good thing, or will it slow down performance? i understand that a single index on a property is meant to have O (log n)

[JohnnyHK]

@bouncingHippo You only want to create the indexes that you actually need to support the query performance you require. Every index adds work when adding/edting documents and they take up disk and memory.

[bouncingHippo]

i edited the question a little would you mind taking a look at my attempt to find all comments by a specific user? thanks!!

[JohnnyHK]

@bouncingHippo Please post that as a separate question as it has nothing to do with indexing.

[bouncingHippo]

ok done stackoverflow.com/questions/13273619/…

[gvaish]

How to define the order while defining the index? docs.mongodb.org/manual/reference/method/…

[JohnnyHK]

@MasterGaurav Order doesn't matter for single key indexes, but if you wanted to specify it you could do that via schema.index.

[Totty.js]

But in my case doesn't call ensureIndex at all with both methods: schema.index or {... index: true, unique: true}

[Randy L]

seemed to work for a 2d index on a legacy-style geo index/query. running on mongo 2.6