Remove the project_authorizations.id columnremove-project-authorizations-id-column

This column used to be a 32 bits integer, allowing for only a maximum of
2 147 483 647 rows. Given enough users one can hit this limit pretty
quickly, as was the case for GitLab.com.

Changing this type to bigint (= 64 bits) would give us more space, but
we'd eventually hit the same limit given enough users and projects. A
much more sustainable solution is to simply drop the "id" column.

There were only 2 lines of code depending on this column being present,
and neither truly required it to be present. Instead the code now uses
the "project_id" column combined with the "user_id" column. This means
that instead of something like this:

    DELETE FROM project_authorizations
    WHERE user_id = X
    AND id = Y;

We now run the following when removing rows:

    DELETE FROM project_authorizations
    WHERE user_id = X
    AND project_id = Y;

Since both user_id and project_id are indexed this should not slow down
the DELETE query.

This commit also removes the "dependent: destroy" clause from the
"project_authorizations" relation in the User and Project models.
Keeping this prevents Rails from being able to remove data as it relies
on an "id" column being present. Since the "project_authorizations"
table has proper foreign keys set up (with cascading removals) we don't
need to depend on any Rails logic.

1 files changed, 2 insertions, 2 deletions

diff --git a/app/models/user.rb b/app/models/user.rb
index 66a768d54bb..06dd98a3188 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -73,7 +73,7 @@ class User < ActiveRecord::Base
   has_many :created_projects,         foreign_key: :creator_id, class_name: 'Project'
   has_many :users_star_projects, dependent: :destroy
   has_many :starred_projects, through: :users_star_projects, source: :project
-  has_many :project_authorizations, dependent: :destroy
+  has_many :project_authorizations
   has_many :authorized_projects, through: :project_authorizations, source: :project
 
   has_many :snippets,                 dependent: :destroy, foreign_key: :author_id
@@ -444,7 +444,7 @@ class User < ActiveRecord::Base
   end
 
   def remove_project_authorizations(project_ids)
-    project_authorizations.where(id: project_ids).delete_all
+    project_authorizations.where(project_id: project_ids).delete_all
   end
 
   def set_authorized_projects_column