We need to recorder here. Need to drop the order from default scope.

Fixes #2832

activerecord/lib/active_record/relation/batches.rb

@@ -62,7 +62,7 @@ def find_in_batches(options = {})
       start = options.delete(:start).to_i
       batch_size = options.delete(:batch_size) || 1000
 
-      relation = relation.except(:order).order(batch_order).limit(batch_size)
+      relation = relation.reorder(batch_order).limit(batch_size)
       records = relation.where(table[primary_key].gteq(start)).all
 
       while records.any?

activerecord/test/cases/batches_test.rb

@@ -113,7 +113,27 @@ def test_find_in_batches_should_not_use_records_after_yielding_them_in_case_orig
         batch.map! { not_a_post }
       end
     end
+  end
 
+  def test_find_in_batches_should_ignore_the_order_default_scope
+    # First post is with title scope
+    first_post = PostWithDefaultScope.first
+    posts = []
+    PostWithDefaultScope.find_in_batches  do |batch|
+      posts.concat(batch)
+    end
+    # posts.first will be ordered using id only. Title order scope should not apply here
+    assert_not_equal first_post, posts.first
+    assert_equal posts(:welcome), posts.first
+  end
+
+  def test_find_in_batches_should_not_ignore_the_default_scope_if_it_is_other_then_order
+    special_posts_ids = SpecialPostWithDefaultScope.all.map(&:id)
+    posts = []
+    SpecialPostWithDefaultScope.find_in_batches do |batch|
+      posts.concat(batch)
+    end
+    assert_equal special_posts_ids, posts.map(&:id)
   end
 
 end

activerecord/test/models/post.rb

@@ -172,3 +172,13 @@ class PostWithDefaultInclude < ActiveRecord::Base
   default_scope includes(:comments)
   has_many :comments, :foreign_key => :post_id
 end
+
+class PostWithDefaultScope < ActiveRecord::Base
+  self.table_name = 'posts'
+  default_scope :order => :title
+end
+
+class SpecialPostWithDefaultScope < ActiveRecord::Base
+  self.table_name = 'posts'
+  default_scope where(:id => [1, 5,6])
+end
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