How can I run updates in batches in Rails 3/4?

Question

I need to mass-update many thousands of records, and I would like to process the updates in batches. First, I tried:

Foo.where(bar: \'bar\').find_in_batches.upda         


        

Answer 1

In Rails 5, there's a new handy method ActiveRecord::Relation#in_batches to solve this problem:

Foo.in_batches.update_all(bar: 'baz')

Check documentation for details.