---
title: "Slow fields"
url: "https://docs.unified.to/reference/slow-fields"
description: "Control performance and completeness when using slow fields with the fields parameter"
generated_at: "2026-05-21T18:13:09.743Z"
---
# Slow fields

Some fields in upstream APIs are expensive to fetch because they require extra API calls per record. We call these **slow fields**.

Slow fields let you choose between **faster responses** and **more complete data**. You control the default behavior at the workspace level, and you can always override it per request with the `fields` query parameter.

---

## [What are slow fields?](#what-are-slow-fields)

**Slow fields** are resource fields that require additional API calls to fetch from the upstream provider.

Examples:

* A job application’s `offers` in Greenhouse requires a separate API call per application.
* Nested raw objects may expose additional slow fields like `raw.offers`.

Because these fields can be expensive to retrieve, we treat them specially:

* They can be **excluded by default** to keep responses fast.
* They can be **included when explicitly requested** using the `fields` parameter.
* Or they can be **included by default** if you prefer completeness over latency.

---

## [Workspace setting: Slow fields opt-in](#workspace-setting-slow-fields-opt-in)

You can control how slow fields behave by default from your workspace settings in the Unified app under **Settings → Workspace → Slow fields opt-in** ([workspace settings](https://app.unified.to/settings/workspace)).

* `false` (**Opt-out / recommended default**)  
  * Slow fields are **excluded by default**.
  * Fewer upstream calls and lower latency.
  * Slow fields are only fetched when explicitly requested via `fields`.
* `true` (**Opt-in**)  
  * Slow fields are **included by default**.
  * Responses are more complete.
  * Responses can be slower due to additional API calls.

You can still override this default on any request using the `fields` parameter. For a general overview of how `fields` works (including raw fields), see [Working with Custom & Original Fields](/reference/fields).

---

## [How slow fields interact with fields=…](#how-slow-fields-interact-with-fields)

You can control which fields are returned using the `fields` query parameter. The behavior depends on how you’ve configured **Slow fields opt-in** for your workspace.

### [When Slow fields opt-in is set to **Opt-out** (default)](#when-slow-fields-opt-in-is-set-to-opt-out-default)

Slow fields are excluded unless you request them:

```
GET /ats/{connection_id}/application

```

Returns standard (fast) fields only.

```
GET /ats/{connection_id}/application?fields=offers

```

Returns only the `offers` field (a slow field; this may trigger extra upstream API calls).

```
GET /ats/{connection_id}/application?fields=job_id,candidate_id

```

Returns only the requested fast fields (no slow fields).

### [When Slow fields opt-in is set to **Opt-in**](#when-slow-fields-opt-in-is-set-to-opt-in)

Slow fields are included unless you filter them out:

```
GET /ats/{connection_id}/application

```

Returns all fields, including slow fields (slower, more complete).

```
GET /ats/{connection_id}/application?fields=job_id,candidate_id

```

Returns only the requested fields (fast, excludes other slow fields).

```
GET /ats/{connection_id}/application?fields=job_id,offers

```

Returns `job_id` plus the `offers` slow field (may trigger extra upstream API calls).

---

## [Raw objects and slow fields](#raw-objects-and-slow-fields)

The same logic applies to nested raw objects:

* `fields=raw.offers`  
Requests the slow `offers` field inside the raw payload.
* `fields=raw.last_activity_at`  
Requests only a non-slow raw field (no extra API calls).

Slow fields are always explicit: if you do not request them (and your workspace is not opted in by default), they will not be fetched.

---

## [When to opt in vs opt out](#when-to-opt-in-vs-opt-out)

**Recommended patterns:**

1. **High‑volume or latency‑sensitive traffic**
  * Set **Slow fields opt-in** to **Opt-out**.
  * Only request slow fields when you actually need them, via `fields=…`.
2. **Comprehensive data syncs or backfills**
  * Set **Slow fields opt-in** to **Opt-in**, _or_
  * Leave it as **Opt-out** and explicitly request all needed slow fields with `fields`.
3. **Webhooks and push-based flows**
  * Configure the `fields` parameter to include only the fields your consumer needs.
  * Avoid including slow fields unless your webhook handler can tolerate the extra latency.

---

## [Identifying which fields are slow](#identifying-which-fields-are-slow)

Slow fields are **integration- and object-specific**. For example:

* **Greenhouse Applications**: `offers`, `raw.offers`

Other integrations and object types may expose different slow fields. To see which fields are slow for a given object, check the integration-specific documentation or contact support.