1 files changed, 68 insertions, 0 deletions
diff --git a/db/migrate/20180403035759_create_project_ci_cd_settings.rb b/db/migrate/20180403035759_create_project_ci_cd_settings.rb
new file mode 100644
index 00000000000..06856af6204
--- /dev/null
+++ b/db/migrate/20180403035759_create_project_ci_cd_settings.rb
@@ -0,0 +1,68 @@
+class CreateProjectCiCdSettings < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def up
+    unless table_exists?(:project_ci_cd_settings)
+      create_table(:project_ci_cd_settings) do |t|
+        t.integer(:project_id, null: false)
+        t.boolean(:group_runners_enabled, default: true, null: false)
+      end
+    end
+
+    disable_statement_timeout
+
+    # This particular INSERT will take between 10 and 20 seconds.
+    execute 'INSERT INTO project_ci_cd_settings (project_id) SELECT id FROM projects'
+
+    # We add the index and foreign key separately so the above INSERT statement
+    # takes as little time as possible.
+    add_concurrent_index(:project_ci_cd_settings, :project_id, unique: true)
+
+    add_foreign_key_with_retry
+  end
+
+  def down
+    drop_table :project_ci_cd_settings
+  end
+
+  def add_foreign_key_with_retry
+    if Gitlab::Database.mysql?
+      # When using MySQL we don't support online upgrades, thus projects can't
+      # be deleted while we are running this migration.
+      return add_project_id_foreign_key
+    end
+
+    # Between the initial INSERT and the addition of the foreign key some
+    # projects may have been removed, leaving orphaned rows in our new settings
+    # table.
+    loop do
+      remove_orphaned_settings
+
+      begin
+        add_project_id_foreign_key
+        break
+      rescue ActiveRecord::InvalidForeignKey
+        say 'project_ci_cd_settings contains some orphaned rows, retrying...'
+      end
+    end
+  end
+
+  def add_project_id_foreign_key
+    add_concurrent_foreign_key(:project_ci_cd_settings, :projects, column: :project_id)
+  end
+
+  def remove_orphaned_settings
+    execute <<~SQL
+      DELETE FROM project_ci_cd_settings
+      WHERE NOT EXISTS (
+        SELECT 1
+        FROM projects
+        WHERE projects.id = project_ci_cd_settings.project_id
+      )
+    SQL
+  end
+end