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

# Connect a data source

> Learn how to connect your warehouse or lakehouse to Openlayer

To monitor data quality, Openlayer needs access to the **tables you want to track**.
You do this by connecting a data source (e.g., BigQuery, Snowflake, Databricks) and selecting the tables of interest.

Once connected, Openlayer will run automated tests directly on top of those tables.

## How to connect

> [!NOTE]
>
> **Prerequisites**:
>
> * An [Openlayer project](https://docs.openlayer.com/workspace-and-projects/creating-and-loading-projects.md) with monitoring mode enabled
> * Appropriate credentials for your data source (see the provider-specific guides)

**1. Choose a provider**

In your project, go to **Data sources** and click **Connect a data source**.
Select your provider:

> [card] [BigQuery](https://docs.openlayer.com/integrations/bigquery.md)

> [card] [Snowflake](https://docs.openlayer.com/integrations/snowflake.md)

> [card] [Databricks](https://docs.openlayer.com/integrations/databricks.md)

Each provider has its own authentication flow. For example, BigQuery supports both
**service account impersonation** and **service account key** uploads.
Follow the provider guide linked above for details.

**2. Enter credentials**

You will be prompted for connection details, such as:

![Configure BigQuery connection](https://mintcdn.com/openlayer-44/uwZVy8AI1ZEo3Xtn/images/documentation/bq_connection.png?fit=max\&auto=format\&n=uwZVy8AI1ZEo3Xtn\&q=85\&s=e1b22dbc07d8395b7404ce11c0550884)

Openlayer stores these securely and uses them only to run queries on your behalf.

**3. Select tables**

Once credentials are verified, you can browse the available databases/schemas and choose which tables to monitor.

For each table, you’ll also configure:

* A **timestamp column** (to order data in monitoring windows)
* An optional **data source name** (to label the connection in Openlayer)

**4. Start monitoring**

After saving, Openlayer will profile the table and begin running data quality tests.
You can then add checks such as schema validation, drift detection, or anomaly detection.

See the [Tests overview](https://docs.openlayer.com/tests/overview.md) for details on configuring tests.

## Next steps

* Connect your first source: [BigQuery guide](https://docs.openlayer.com/integrations/bigquery.md)
* Learn how to [add data quality tests](https://docs.openlayer.com/tests/overview.md)


This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.