I’m trying to understand more about the telemetry events emitted from a poorly performing query.

I’m looking at the AppSignal dashboard which records the events and puts them into a timeline.

The query has many preloads, but they don’t seem to show up in the timeline:

My questions:

• Why is only one of the preloads showing up in each of the screenshots above?
• Is that dead-time between the first query and the last preload just time spend doing the preloads? Is that expected? if not is this likely a telemetry events issue or an appsignal issue?

The offending code:

# in data_plugs
  @decorate transaction_event()
  def add_project_offers_to_conn(conn, _ops) do
    project = conn.assigns.project
    offers = Production.list_offers([project_id: project.id], [:custom_fields])

    conn
    |> assign(:proj_offers, offers)
  end

  def list_offers(filters, preloads \\ []) when is_list(filters) and is_list(preloads) do
    preloads =
      preloads ++
        [
          :engagement,
          :original_offer,
          :replacement_offer,
          :job_title,
          :department,
          :contract_type,
          :document,
          altered_documents: :document,
          envelope_events: EnvelopeEventAPI.preload_query()
        ]

    query =
      from(o in Offer, preload: ^preloads)
      |> Queries.apply_filters(filters)

    Repo.all(query)
  end