1 files changed, 55 insertions, 0 deletions
diff --git a/db/migrate/20161014173530_create_label_priorities.rb b/db/migrate/20161014173530_create_label_priorities.rb
new file mode 100644
index 00000000000..f9d94ebdc70
--- /dev/null
+++ b/db/migrate/20161014173530_create_label_priorities.rb
@@ -0,0 +1,55 @@
+class CreateLabelPriorities < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = true
+  DOWNTIME_REASON = 'Prioritezed labels will not work as expected until this migration is complete.'
+
+  disable_ddl_transaction!
+
+  def up
+    create_table :label_priorities do |t|
+      t.references :project, foreign_key: { on_delete: :cascade }, null: false
+      t.references :label, foreign_key: { on_delete: :cascade }, null: false
+      t.integer :priority, null: false
+
+      t.timestamps null: false
+    end
+
+    execute <<-EOF.strip_heredoc
+      INSERT INTO label_priorities (project_id, label_id, priority, created_at, updated_at)
+      SELECT labels.project_id, labels.id, labels.priority, NOW(), NOW()
+      FROM labels
+      WHERE labels.project_id IS NOT NULL
+        AND labels.priority IS NOT NULL;
+    EOF
+
+    add_concurrent_index :label_priorities, [:project_id, :label_id], unique: true
+    add_concurrent_index :label_priorities, :priority
+
+    remove_column :labels, :priority
+  end
+
+  def down
+    add_column :labels, :priority, :integer
+
+    if Gitlab::Database.mysql?
+      execute <<-EOF.strip_heredoc
+        UPDATE labels
+          INNER JOIN label_priorities ON labels.id = label_priorities.label_id AND labels.project_id = label_priorities.project_id
+        SET labels.priority = label_priorities.priority;
+      EOF
+    else
+      execute <<-EOF.strip_heredoc
+        UPDATE labels
+        SET priority = label_priorities.priority
+        FROM label_priorities
+        WHERE labels.id = label_priorities.label_id
+          AND labels.project_id = label_priorities.project_id;
+      EOF
+    end
+
+    add_concurrent_index :labels, :priority
+
+    drop_table :label_priorities
+  end
+end