mongo-batch is not maintained anymore.

A Ruby library to run Mongoid queries on large collections in batches.

Supported Ruby versions: 2.1, 2.2
Supported Mongoid versions: 4.0, 5.0

gem install mongo_batch -v '~> 0.1'

Or, in your Gemfile:

gem 'mongo_batch', '~> 0.1'

Extend your Mongoid models with MongoBatch to be able to call find_in_batches on your models. The method will yield each batch of records to the given block.

require 'mongo_batch'

class Post
  extend MongoBatch
end

Post.find_in_batches do |batch|
  batch.each do |post|
    post.update(body: 'Hello world!')
  end
end

If you do not pass a block to find_in_batches, the method will return an Enumerator.

Post.find_in_batches.with_index.each do |batch, index|
  batch.each do |post|
    post.update(body: "Hello world! #{index}")
  end
end

The default batch size is 1,000 records, but find_in_batches accepts an option to configure a different batch size, as well as options to limit the records to process, sorting criteria and an initial offset.

Post
  .find_in_batches(batch_size: 500, to: 2_000, offset: 100, order_by: { _id: :desc })
  .each do |batch|
    batch.each do |post|
      post.update(body: "Hola mundo!")
    end
end

If you have more complex queries or prefer not to extend your models with MongoBatch, you can use MongoBatch.in_batches and supply the query you want to batch.

MongoBatch
  .in_batches(Post.where(:body.exists => true).no_timeout)
  .each do |batch|
    batch.each do |post|
      post.update(body: 'Hello world!')
    end
end

MongoBatch.in_batches also accepts values to configure the batch size, limit of records to process, sorting criteria or an initial offset.

MongoBatch
  .in_batches(Post.where(:body.exists => true).no_timeout,
              to: 2_000, offset: 100, order_by: { _id::desc })
  .each do |batch|
     batch.each do |post|
       post.update(body: 'Hi mum!')
     end
  end

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