Calculates time between updated_at and created_at from all databases

calc_time_all_databases.rb

Mongo::Logger.logger.level = Logger::FATAL
mongo_client = Mongo::Client.new(['127.0.0.1'])

ignore_dbs = [
  'admin',
  'config',
].freeze

dbs_data = mongo_client.list_mongo_databases.reject { |db| ignore_dbs.include?(db.name) }.map do |mongo_database|
  puts mongo_database.name
  
  collections = mongo_database.collections.map do |collection|
    puts "- #{collection.name}"
    
    query_filter = {
      # some filter
    }
    limit = 100
    query = collection.find(query_filter).sort({ created_at: -1 }).limit(limit)

    time_to_process_array = query.map do |document|
      updated_at = document['updated_at']
      created_at = document['created_at']
      next 0 unless [updated_at, created_at].all? { |time| time.instance_of?(Time) }

      updated_at - created_at
    end

    empty = time_to_process_array.size == 0
    {
      name: collection.name,
      total_document: collection.count_documents({}),
      time_to_process_min: empty ? 0 : time_to_process_array.min,
      time_to_process_max: empty ? 0 : time_to_process_array.max,
      time_to_process_average: empty ? 0 : time_to_process_array.sum / time_to_process_array.size.to_f,
    }
  end

  {
    name: mongo_database.name,
    collections: collections,
  }
end
mongo_client.close

puts JSON.pretty_generate(dbs_data)