> ## Documentation Index
> Fetch the complete documentation index at: https://docs.hightouch.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Audience snapshots

> Audience snapshots record who was in an audience and when members entered or exited. Hightouch writes this history to your warehouse as a table you can query.

Audience [dashboards](https://docs.hightouch.com/customer-studio/audience-overviews.md) show membership trends inside Hightouch. Snapshots store audience membership changes in your warehouse, where you can query them directly or join them with other data for reporting and analysis.

## Before you begin

* A source with the [Lightning sync engine](https://docs.hightouch.com/syncs/lightning-sync-engine.md) enabled
* Warehouse [source](https://docs.hightouch.com/getting-started/concepts.md#sources) with **write** permissions

## How snapshots work

After each successful audience sync, Customer Studio writes membership changes to the snapshot table. Each record includes:

* **Audience member ID** — The primary key of the audience member.
* **Timestamp** — When the member entered or exited the audience.
* **Event type** — Either `enter` or `exit`.
* **Split group ID** — The member's split group when audience [experiments](https://docs.hightouch.com/customer-studio/experiments.md) are enabled.

The first snapshot records every current audience member as an `enter` event. Later snapshots record only changes since the previous snapshot:

* an `enter` event when a member joins the audience
* an `exit` event when a member leaves the audience

## Snapshot table schema

Snapshots are stored in a shared table in the [Hightouch Planner schema](https://docs.hightouch.com/syncs/lightning-sync-engine.md#warehouse-schemas): `hightouch_planner.audience_membership`.

| Column | Type | Description |
| - | - | - |
| `ht_row_id` | `string` | The primary key of the audience member. Hightouch converts the value to a string when needed. |
| `ht_audience_id` | `string` | The ID of the audience. |
| `ht_timestamp` | `timestamp` | When the member entered or exited the audience. |
| `ht_event_type` | `string` | Either `enter` or `exit`. |
| `ht_split_group` | `string` | The split group ID the member belongs to, or `null` if no split was applied. |

## Enable snapshots

Audience snapshots are configured as part of [warehouse sync logs](https://docs.hightouch.com/syncs/warehouse-sync-logs.md) and enabled per source:

1. Go to your [source](https://docs.hightouch.com/getting-started/concepts.md#sources).
2. Open the **Sync logs** tab.
3. Under **Warehouse sync logs**, enable **Audience snapshots**.

Hightouch records membership changes automatically after each successful audience sync.

![Enable audience snapshots](https://mintcdn.com/hightouch-3c037897/L_vQfA0JQEpeGUUo/images/hightouch-audiences/performance/enable-snapshot.png?fit=max\&auto=format\&n=L_vQfA0JQEpeGUUo\&q=85\&s=7471a954fcc4a6d4c44cb198d8e50596)