# updated\_at

(Applies to dbt v1.9 and later)

snapshots/snapshots.yml

```yaml
snapshots:
  - name: snapshot
    relation: source('my_source', 'my_table')
    config:
      strategy: timestamp
      updated_at: column_name
```

dbt\_project.yml

```yml
snapshots:
  <resource-path>:
    +strategy: timestamp
    +updated_at: column_name
```

(Applies to dbt v1.9 and later)

caution

You will get a warning if the data type of the `updated_at` column does not match the adapter-configured default.

## Description

A column within the results of your snapshot query that represents when the record row was last updated.

This parameter is **required if using the `timestamp` [strategy](./strategy.md)**. The `updated_at` field may support ISO date strings and unix epoch integers, depending on the data platform you use.

## Default

No default is provided.

## Examples

### Use a column name `updated_at`

(Applies to dbt v1.9 and later)

snapshots/orders\_snapshot.yml

```yaml
snapshots:
  - name: orders_snapshot
    relation: source('jaffle_shop', 'orders')
    config:
      schema: snapshots
      unique_key: id
      strategy: timestamp
      updated_at: updated_at
```

### Coalesce two columns to create a reliable `updated_at` column

Consider a data source that only has an `updated_at` column filled in when a record is updated (so a `null` value indicates that the record hasn't been updated after it was created).

Since the `updated_at` configuration only takes a column name, rather than an expression, you should update your snapshot query to include the coalesced column.

(Applies to dbt v1.9 and later)

1. Create an staging model to perform the transformation. In your `models/` directory, create a SQL file that configures an staging model to coalesce the `updated_at` and `created_at` columns into a new column `updated_at_for_snapshot`.

   models/staging\_orders.sql

   ```sql
   select  * coalesce (updated_at, created_at) as updated_at_for_snapshot
   from {{ source('jaffle_shop', 'orders') }}
   ```

2. Define the snapshot configuration in a YAML file. In your `snapshots/` directory, create a YAML file that defines your snapshot and references the `updated_at_for_snapshot` staging model you just created.

   snapshots/orders\_snapshot.yml

   ```yaml
   snapshots:
     - name: orders_snapshot
       relation: ref('staging_orders')
       config:
         schema: snapshots
         unique_key: id
         strategy: timestamp
         updated_at: updated_at_for_snapshot
   ```

3. Run `dbt snapshot` to execute the snapshot.

Alternatively, you can also create an ephemeral model to performs the required transformations. Then, you reference this model in your snapshot's `relation` key.

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