什么是建立在Rails的质量HABTM协会的最快方法是什么？ [英] What is the fastest way to create mass HABTM associations in Rails?

问题描述

我有两个表，在Rails的一个HABTM关系。类似如下：

I have two tables, with a HABTM relationship in Rails. Something like the following:

class Foo < ActiveRecord::Base
  has_and_belongs_to_many :bars
end

class Bar < ActiveRecord::Base
  has_and_belongs_to_many :foos
end

现在我有一个新的富对象，并希望大众分配几千条吧，我已经pre装：

Now I have a new Foo object, and want to mass-assign thousands of bars to it, which I've pre-loaded:

@foo = Foo.create
@bars = Bar.find_all_by_some_attribute(:a)

什么是做到这一点的最快方法？我尝试过：

What's the fastest way to do this? I've tried:

@foo.bars = @bars
@foo.bars << @bars

和两个运行速度很慢，用类似下面的每个栏的条目：

And both run really slow, with an entry like the following for each bar:

bars_foos列（1.1ms）SHOW   FIELDS FROM bars_foos SQL（0.6ms）   INSERT INTO bars_foos （ bar_id ，    foo_id ）VALUES（100，117200）

bars_foos Columns (1.1ms) SHOW FIELDS FROM bars_foos SQL (0.6ms) INSERT INTO bars_foos (bar_id, foo_id) VALUES (100, 117200)

我看着AR-扩展，但进口功能似乎并不没有一个模型（Model.import），其中$ P $工作pcludes其使用了连接表。

I looked at ar-extensions, but the import function doesn't seem to work without a model (Model.import) which precludes its use for a join table.

我是否需要写SQL，还是Rails的有prettier方式？

Do I need to write the SQL, or does Rails have a prettier way?

推荐答案

我认为最好的性能代价将是使用SQL和批量插入多行每次查询。如果你可以建立做类似的INSERT语句：

I think your best bet performance-wise is going to be to use SQL, and bulk insert multiple rows per query. If you can build an INSERT statement that does something like:

INSERT INTO foos_bars (foo_id,bar_id) VALUES (1,1),(1,2),(1,3)....

您应该能够插入数千行的一个查询。我没有尝试你mass_habtm方法，但好像你可能喜欢的东西：

You should be able to insert thousands of rows in a single query. I didn't try your mass_habtm method, but it seems like you could to something like:

bars = Bar.find_all_by_some_attribute(:a)
foo = Foo.create
values = bars.map {|bar| "(#{foo.id},#{bar.id})"}.join(",")
connection.execute("INSERT INTO foos_bars (foo_id, bar_id) VALUES #{values}")

另外，如果你是some_attribute搜索栏，请确保您的数据库有一个字段建立索引。

Also, if you are searching Bar by "some_attribute", make sure you have that field indexed in your database.

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