Rails构建并大量保存

Question

I've got something like the following:

module Bar < ActiveRecord::Base
  belongs_to :foo
  ...

module Foo < ActiveRecord::Base
  has_many :bars, dependent: :destroy

  def build_bars
    1000.times do |i|
      bars.build(num: i)
    end
  end

  def create_default_bars!
    build_bars
    save
  end

Notice that Foo#build_bars is cheap. Even though it loops 1000 times, it takes very little time. But then, once you hit save , suddenly ActiveRecord decides to perform 1000 inserts, which is incredibly slow.

How can I write a custom save_the_bars method such that it performs a single bulk INSERT query for all of the bars I have built up (I remind you, the 1000 build s are apparently very cheap), but which functions as a drop-in replacement for save in this example?

---

I'm expecting an answer along the lines of recommendation #3 of this blog post:

https://www.coffeepowered.net/2009/01/23/mass-inserting-data-in-rails-without-killing-your-performance/

But since my example uses build and relies on some slightly nontrivial rails magic, it isn't immediately obvious how to translate it over. Bonus points for benchmarks!

Answer 1

I would try the activerecord-import gem.

def save_the_bars(bars)
  Bars.import bars
end

This call to import does whatever is most efficient for the underlying database adapter. Pretty slick, eh?

For bonus points: Benchmarks

---

Question-asker here, hijacking this answer with details on what I did following the above suggestion:

def build_bars
  built_bars = []
  1000.times do |i|
    built_bars << bars.build(num: i)
  end
  built_bars
end

def create_default_bars
  save
  Bar.insert built_bars, validate: false
  reload
end

This gave a nice speedup for relatively little effort. I still suspect that more speedup could be had (by leveraging the nuances of insert ) but I'm satisfied with this for now. In my use case, it was safe to turn off validation, since the method generating all the Bar s is guaranteed to generate valid ones.