Collection Configuration

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Overview

Configure Collection Options
Time Series Collection
Capped Collection
Default Collation
Collection Management Rake Task

Overview

In this guide, you can learn how to specify configuration options for a collection in your Mongoid application.

Configure Collection Options

You can specify configuration options for a collection by using the :collection_options argument with the store_in macro. The :collection_options argument accepts any collection option that your Ruby driver and MongoDB Server versions support.

Note

You must explicitly create a collection to apply any specified collection options. Create your collection by running the collection management Rake task, as shown in Collection Management Rake Task section of this guide.

To learn more about collection options available in the Ruby driver, see the Collections guide in the Ruby driver documentation.

The following sections show examples of how to configure collection options when using Mongoid.

Time Series Collection

Time series collections efficiently store sequences of measurements over a period of time. The following example shows how to configure a time series collection:

class Measurement
  include Mongoid::Document
  field :temperature, type: Integer
  field :timestamp, type: Time
  store_in collection_options: {
    time_series: {
      timeField: "timestamp",
      granularity: "minutes"
    },
    expire_after: 604800
  }
end

To learn more about time series collections, see the Time Series Collections guide in the MongoDB Server manual.

Capped Collection

Capped collections have maximum size or document counts that prevent them from growing beyond a specified threshold. The following example shows how to configure a capped collection:

class Blog
  include Mongoid::Document
  store_in collection_options: {
    capped: true,
    size: 1024
  }
end

To learn more about capped collections, see the Capped Collections guide in the MongoDB Server manual.

Default Collation

Collations are sets of rules for how to compare strings, typically in a particular natural language. The following example shows how to specify a default collation to use on a collection:

class Title
  include Mongoid::Document
  store_in collection_options: {
    collation: {
      locale: 'fr'
    }
  }
end

To learn more about collations, see the Collation guide in the MongoDB Server manual.

Collection Management Rake Task

To apply the collection options you specify in your Mongoid application, you must explicitly create the corresponding collection. To do so, use the db:mongoid:create_collections Rake task by running the following command in your shell:

rake db:mongoid:create_collections

You can also run the create_collection command on a single model in the Rails console, as shown in the following example:

Model.create_collection

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