add offset support to delete_all

Change-Id: I102ba8628d60dbaeea8ebeb9335c655bc822648e
Reviewed-on: https://gerrit.instructure.com/69453
Reviewed-by: Simon Williams <simon@instructure.com>
Tested-by: Jenkins
Product-Review: Cody Cutrer <cody@instructure.com>
QA-Review: Cody Cutrer <cody@instructure.com>

config/initializers/active_record.rb

@@ -870,17 +870,9 @@ ActiveRecord::Relation.class_eval do
   alias_method_chain :delete_all, :joins
 
   def delete_all_with_limit(conditions = nil)
-    if limit_value
-      case connection.adapter_name
-      when 'MySQL', 'Mysql2'
-        v = arel.visitor
-        sql = "DELETE #{quoted_table_name} FROM #{quoted_table_name} #{arel.where_sql}
-            ORDER BY #{arel.orders.map { |x| v.send(:visit, x) }.join(', ')} LIMIT #{v.send(:visit, arel.limit)}"
-        return connection.delete(sql, "#{name} Delete all")
-      else
-        scope = except(:select).select("#{quoted_table_name}.#{primary_key}")
-        return unscoped.where(primary_key => scope).delete_all
-      end
+    if limit_value || offset_value
+      scope = except(:select).select("#{quoted_table_name}.#{primary_key}")
+      return unscoped.where(primary_key => scope).delete_all
     end
     delete_all_without_limit(conditions)
   end

spec/models/active_record_base_spec.rb

@@ -548,6 +548,17 @@ describe ActiveRecord::Base do
       p1.reload
       expect { p2.reload }.to raise_error(ActiveRecord::RecordNotFound)
     end
+
+    it "does offset too" do
+      u = User.create!
+      p1 = u.pseudonyms.create!(unique_id: 'a', account: Account.default)
+      p2 = u.pseudonyms.create!(unique_id: 'b', account: Account.default)
+      p3 = u.pseudonyms.create!(unique_id: 'c', account: Account.default)
+      u.pseudonyms.scoped.reorder("unique_id DESC").limit(1).offset(1).delete_all
+      p1.reload
+      expect { p2.reload }.to raise_error(ActiveRecord::RecordNotFound)
+      p3.reload
+    end
   end
 
   describe "add_index" do