Mongoose compound indexes not being created (Too long)

Question

I'm having some issues creating multiple compound indexes on one of my schemas in MongoDB. When using MongoLab, I know some indexes are not created when they are too long, due to a naming issue. So I suspect this might be the reason why some are not created

var Schema = new mongoose.Schema({ ... });

// Created
Schema.index({
    one: 1,
    three: 1
});

// Not Created
Schema.index({
    one: 1,
    two: 1,
    three: 1,
    four: 1,
    five: 1,
    six: 1,
    seven: 1,
    eight: 1,
    nine: 1,
    ten: 1
});

Galloromance

does it print some thing to the screen when create 2nd index ? how do you know that the second index is not created ?Did you check in mongo shell ? – Induction

@Induction I didn't add any logging yet. I did check the mongo shell and it wasn't created, hence how I know. When I manually try to create that index, i get the following: "The default index name generated by MongoDB is too long. Please specify a custom name." – Galloromance

Your right, there is a limitation to the default index name (docs.mongodb.org/manual/reference/limits/#Index-Name-Length) You can specify custom name by passing addition option to Schema.index Schema.index({ one: 1, two: 1, three: 1, four: 1, five: 1, six: 1, seven: 1, eight: 1, nine: 1, ten: 1 }, { name: 'my_index_name' } ); – Induction

Thanks, that was exactly what I was looking for – Galloromance

@Induction Can you add that as an answer, then I can mark it as solved – Galloromance

Answer 1

There is a limitation to the default index name (https://docs.mongodb.org/manual/reference/limits/#Index-Name-Length)

You can specify custom index name by passing addition option object to Schema.index

Schema.index({
    one: 1,
    two: 1,
    three: 1,
    four: 1,
    five: 1,
    six: 1,
    seven: 1,
    eight: 1,
    nine: 1,
    ten: 1 }, 
    { name: 'my_index_name' }
);

Induction

“By default, <index name> is the concatenation of the field names and index type. You can explicitly specify the <index name> to the createIndex() method to ensure that the fully qualified index name does not exceed the limit.” “Fully qualified index names, which includes the namespace and the dot separators (i.e. <database name>.<collection name>.$<index name>), cannot be longer than 128 characters.” – Dm