remove duplication

db/migrate/20150306023106_fix_namespace_duplication.rb

+class FixNamespaceDuplication < ActiveRecord::Migration
+  def up
+    #fixes path duplication
+    select_all('SELECT MAX(id) max, COUNT(id) cnt, path FROM namespaces GROUP BY path HAVING COUNT(id) > 1').each do |nms|
+      bad_nms_ids = select_all("SELECT id FROM namespaces WHERE path = '#{nms['path']}' AND id <> #{nms['max']}").map{|x| x["id"]}
+      execute("UPDATE projects SET namespace_id = #{nms["max"]} WHERE namespace_id IN(#{bad_nms_ids.join(', ')})")
+      execute("DELETE FROM namespaces WHERE id IN(#{bad_nms_ids.join(', ')})")
+    end
+
+    #fixes name duplication
+    select_all('SELECT MAX(id) max, COUNT(id) cnt, name FROM namespaces GROUP BY name HAVING COUNT(id) > 1').each do |nms|
+      bad_nms_ids = select_all("SELECT id FROM namespaces WHERE name = '#{nms['name']}' AND id <> #{nms['max']}").map{|x| x["id"]}
+      execute("UPDATE projects SET namespace_id = #{nms["max"]} WHERE namespace_id IN(#{bad_nms_ids.join(', ')})")
+      execute("DELETE FROM namespaces WHERE id IN(#{bad_nms_ids.join(', ')})")
+    end
+  end
+
+  def down
+    # not implemented
+  end
+end

db/migrate/20150306023112_add_unique_index_to_namespace.rb

 class AddUniqueIndexToNamespace < ActiveRecord::Migration
   def change
-    remove_index :namespaces, :name
-    remove_index :namespaces, :path
+    remove_index :namespaces, column: :name if index_exists?(:namespaces, :name)
+    remove_index :namespaces, column: :path if index_exists?(:namespaces, :path)
 
     add_index :namespaces, :name, unique: true
     add_index :namespaces, :path, unique: true