Use raw SQL instead of Rails models in migrations where appropriate

Closes #14694.

db/migrate/20130218141258_convert_closed_to_state_in_issue.rb

 class ConvertClosedToStateInIssue < ActiveRecord::Migration
+  include Gitlab::Database
+
   def up
-    Issue.transaction do
-      Issue.where(closed: true).update_all(state: :closed)
-      Issue.where(closed: false).update_all(state: :opened)
-    end
+    execute "UPDATE #{table_name} SET state = 'closed' WHERE closed = #{true_value}"
+    execute "UPDATE #{table_name} SET state = 'opened' WHERE closed = #{false_value}"
   end
 
   def down
-    Issue.transaction do
-      Issue.where(state: :closed).update_all(closed: true)
-    end
+    execute "UPDATE #{table_name} SET closed = #{true_value} WHERE state = 'closed'"
+  end
+
+  private
+
+  def table_name
+    Issue.table_name
   end
 end

db/migrate/20130218141327_convert_closed_to_state_in_merge_request.rb

 class ConvertClosedToStateInMergeRequest < ActiveRecord::Migration
+  include Gitlab::Database
+
   def up
-    MergeRequest.transaction do
-      MergeRequest.where(closed: true, merged: true).update_all(state: :merged)
-      MergeRequest.where(closed: true, merged: false).update_all(state: :closed)
-      MergeRequest.where(closed: false).update_all(state: :opened)
-    end
+    execute "UPDATE #{table_name} SET state = 'merged' WHERE closed = #{true_value} AND merged = #{true_value}"
+    execute "UPDATE #{table_name} SET state = 'closed' WHERE closed = #{true_value} AND merged = #{false_value}"
+    execute "UPDATE #{table_name} SET state = 'opened' WHERE closed = #{false_value}"
   end
 
   def down
-    MergeRequest.transaction do
-      MergeRequest.where(state: :closed).update_all(closed: true)
-      MergeRequest.where(state: :merged).update_all(closed: true, merged: true)
-    end
+    execute "UPDATE #{table_name} SET closed = #{true_value} WHERE state = 'closed'"
+    execute "UPDATE #{table_name} SET closed = #{true_value}, merged = #{true_value} WHERE state = 'merged'"
+  end
+
+  private
+
+  def table_name
+    MergeRequest.table_name
   end
 end

db/migrate/20130218141344_convert_closed_to_state_in_milestone.rb

 class ConvertClosedToStateInMilestone < ActiveRecord::Migration
+  include Gitlab::Database
+
   def up
-    Milestone.transaction do
-      Milestone.where(closed: true).update_all(state: :closed)
-      Milestone.where(closed: false).update_all(state: :active)
-    end
+    execute "UPDATE #{table_name} SET state = 'closed' WHERE closed = #{true_value}"
+    execute "UPDATE #{table_name} SET state = 'active' WHERE closed = #{false_value}"
   end
 
   def down
-    Milestone.transaction do
-      Milestone.where(state: :closed).update_all(closed: true)
-    end
+    execute "UPDATE #{table_name} SET closed = #{true_value} WHERE state = 'cloesd'"
+  end
+
+  private
+
+  def table_name
+    Milestone.table_name
   end
 end

db/migrate/20130220125544_convert_merge_status_in_merge_request.rb

 class ConvertMergeStatusInMergeRequest < ActiveRecord::Migration
   def up
-    MergeRequest.transaction do
-      MergeRequest.where(merge_status: 1).update_all("new_merge_status = 'unchecked'")
-      MergeRequest.where(merge_status: 2).update_all("new_merge_status = 'can_be_merged'")
-      MergeRequest.where(merge_status: 3).update_all("new_merge_status = 'cannot_be_merged'")
-    end
+    execute "UPDATE #{table_name} SET new_merge_status = 'unchecked' WHERE merge_status = 1"
+    execute "UPDATE #{table_name} SET new_merge_status = 'can_be_merged' WHERE merge_status = 2"
+    execute "UPDATE #{table_name} SET new_merge_status = 'cannot_be_merged' WHERE merge_status = 3"
   end
 
   def down
-    MergeRequest.transaction do
-      MergeRequest.where(new_merge_status: :unchecked).update_all("merge_status = 1")
-      MergeRequest.where(new_merge_status: :can_be_merged).update_all("merge_status = 2")
-      MergeRequest.where(new_merge_status: :cannot_be_merged).update_all("merge_status = 3")
-    end
+    execute "UPDATE #{table_name} SET merge_status = 1 WHERE new_merge_status = 'unchecked'"
+    execute "UPDATE #{table_name} SET merge_status = 2 WHERE new_merge_status = 'can_be_merged'"
+    execute "UPDATE #{table_name} SET merge_status = 3 WHERE new_merge_status = 'cannot_be_merged'"
+  end
+
+  private
+
+  def table_name
+    MergeRequest.table_name
   end
 end

db/migrate/20130419190306_allow_merges_for_forks.rb

 class AllowMergesForForks < ActiveRecord::Migration
   def self.up
     add_column :merge_requests, :target_project_id, :integer, :null => true
-    MergeRequest.update_all("target_project_id = project_id")
+    execute "UPDATE #{table_name} SET target_project_id = project_id"
     change_column :merge_requests, :target_project_id, :integer, :null => false
     rename_column :merge_requests, :project_id, :source_project_id
   end
@@ -10,4 +10,10 @@ class AllowMergesForForks < ActiveRecord::Migration
     remove_column :merge_requests, :target_project_id
     rename_column :merge_requests, :source_project_id,:project_id
   end
+
+  private
+
+  def table_name
+    MergeRequest.table_name
+  end
 end