1 files changed, 38 insertions, 0 deletions
diff --git a/db/migrate/20170622135728_add_unique_constraint_to_ci_variables.rb b/db/migrate/20170622135728_add_unique_constraint_to_ci_variables.rb
new file mode 100644
index 00000000000..8b2cc40ee59
--- /dev/null
+++ b/db/migrate/20170622135728_add_unique_constraint_to_ci_variables.rb
@@ -0,0 +1,38 @@
+class AddUniqueConstraintToCiVariables < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def up
+    unless this_index_exists?
+      add_concurrent_index(:ci_variables, columns, name: index_name, unique: true)
+    end
+  end
+
+  def down
+    if this_index_exists?
+      if Gitlab::Database.mysql? && !index_exists?(:ci_variables, :project_id)
+        # Need to add this index for MySQL project_id foreign key constraint
+        add_concurrent_index(:ci_variables, :project_id)
+      end
+
+      remove_concurrent_index(:ci_variables, columns, name: index_name)
+    end
+  end
+
+  private
+
+  def this_index_exists?
+    index_exists?(:ci_variables, columns, name: index_name)
+  end
+
+  def columns
+    @columns ||= [:project_id, :key, :environment_scope]
+  end
+
+  def index_name
+    'index_ci_variables_on_project_id_and_key_and_environment_scope'
+  end
+end