Method: ActiveRecord::Relation#load_async

Defined in:

activerecord/lib/active_record/relation.rb

#load_async ⇒ Object

Schedule the query to be performed from a background thread pool.

Post.where(published: true).load_async # => #<ActiveRecord::Relation>

When the Relation is iterated, if the background query wasn’t executed yet, it will be performed by the foreground thread.

Note that config.active_record.async_query_executor must be configured for queries to actually be executed concurrently. Otherwise it defaults to executing them in the foreground.

load_async will also fall back to executing in the foreground in the test environment when transactional fixtures are enabled.

If the query was actually executed in the background, the Active Record logs will show it by prefixing the log line with ASYNC:

ASYNC Post Load (0.0ms) (db time 2ms)  SELECT "posts".* FROM "posts" LIMIT 100

# File 'activerecord/lib/active_record/relation.rb', line 696

def load_async
  return load if !connection.async_enabled?

  unless loaded?
    result = exec_main_query(async: connection.current_transaction.closed?)

    if result.is_a?(Array)
      @records = result
    else
      @future_result = result
    end
    @loaded = true
  end

  self
end