1 files changed, 40 insertions, 0 deletions
diff --git a/db/migrate/20180320182229_add_indexes_for_user_activity_queries.rb b/db/migrate/20180320182229_add_indexes_for_user_activity_queries.rb
new file mode 100644
index 00000000000..824bbb3ac05
--- /dev/null
+++ b/db/migrate/20180320182229_add_indexes_for_user_activity_queries.rb
@@ -0,0 +1,40 @@
+class AddIndexesForUserActivityQueries < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def up
+    add_concurrent_index :events, [:author_id, :project_id] unless index_exists?(:events, [:author_id, :project_id])
+    add_concurrent_index :user_interacted_projects, :user_id unless index_exists?(:user_interacted_projects, :user_id)
+  end
+
+  def down
+    remove_concurrent_index :events, [:author_id, :project_id] if index_exists?(:events, [:author_id, :project_id])
+
+    patch_foreign_keys do
+      remove_concurrent_index :user_interacted_projects, :user_id if index_exists?(:user_interacted_projects, :user_id)
+    end
+  end
+
+  private
+
+  def patch_foreign_keys
+    return yield if Gitlab::Database.postgresql?
+
+    # MySQL doesn't like to remove the index with a foreign key using it.
+    remove_foreign_key :user_interacted_projects, :users if fk_exists?(:user_interacted_projects, :user_id)
+
+    yield
+
+    # Let's re-add the foreign key using the existing index on (user_id, project_id)
+    add_concurrent_foreign_key :user_interacted_projects, :users, column: :user_id unless fk_exists?(:user_interacted_projects, :user_id)
+  end
+
+  def fk_exists?(table, column)
+    foreign_keys(table).any? do |key|
+      key.options[:column] == column.to_s
+    end
+  end
+end