# Accessing Data Sources

## Accessing Data Sources

Once a source has been[ synced to your environment](/lakehouse-platform/develop-with-dex/sync-sources.md), it becomes fully accessible for exploration, inspection, and usage within your models in dex. This includes sources automatically ingested by native Connectors or manually configured via Sync Sources.

### Browsing Source Files

To view a synced source:

1. Navigate to the **Develop** section in the left-hand menu.
2. On the **Explorer** tab, locate the `.yml` file of the synced source dataset. These files describe the schema (metadata) of your external dataset.
3. Click the `.yml` file to open it in the editor. The file will display a structured list of tables and fields found in that dataset.

### Inspecting Tables and Previewing Data

<figure><img src="/files/K2Cx8tN2TPEfiaUxpXLm" alt=""><figcaption><p>Table Description Menu</p></figcaption></figure>

To inspect a specific table:

1. Right-click on the `.yml` file of the synced source.
2. Go to **Table Description** and choose the table you want to inspect.
3. A right-hand panel will appear showing:
   * Table name and last modified time
   * Storage metadata (partitioning, clustering, size, etc.)
   * Schema including field names, types, and nullability
   * Preview of the raw data
   * Execution logs
   * Lineage for tracking upstream and downstream dependencies

This feature allows you to explore datasets directly within dex, without switching tools or writing queries manually.

### Referencing Sources in Models

When developing models, you can reference raw tables from external datasets using the `source()` function. This is helpful when your transformations depend on data that hasn’t been modeled yet, such as staging or bronze-level data.

To reference a source:

1. Right-click the `.yml` file
2. Navigate to **Copy as Source** and select the table you want to use.
3. dex will copy the correct syntax to your clipboard.

Example:

<pre class="language-sql"><code class="lang-sql"><strong>{{ source('dex-dsm-ecommerce_landing', 'orders') }}
</strong></code></pre>

Paste this reference into your transformation model to query the external data.

#### Example in a real query:

```sql
select
    order_status as order_status,
    safe_cast(order_delivered_customer_date as datetime) as order_delivered_customer_date,
    safe_cast(order_purchase_timestamp as datetime) as order_purchase_timestamp,
    safe_cast(order_estimated_delivery_date as datetime) as order_estimated_delivery_date,
    regexp_extract(customer_id, r'^.{0,3}') as customer_id,
    order_id as order_id,
    safe_cast(order_delivered_carrier_date as datetime) as order_delivered_carrier_date,
    safe_cast(order_approved_at as datetime) as order_approved_at
from 
    {{ source('dex-dsm-ecommerce_landing', 'orders') }}
```

### Ref vs Source

When modeling data in dex, it's important to use the appropriate reference function:

* **`ref()`** is used to reference another model inside your project. It ensures proper dependency resolution and enables dex to build DAGs automatically.

  Example:

  ```sql
  {{ ref('customers_orders') }}
  ```
* **`source()`** is used to reference external datasets that are not defined as models (e.g., raw tables in your warehouse). It is used primarily in the bronze layer or when ingesting data.

  Example:

  ```sql
  {{ source('dex-dsm-ecommerce_landing', 'orders') }}
  ```

Use `ref()` for internal model dependencies and `source()` to bring in raw, external data.


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