Microsoft OneLake Enterprise

Microsoft OneLake is a single, unified, logical data lake that comes automatically with every Microsoft Fabric tenant. It is built on top of Azure Data Lake Storage (ADLS) Gen2. All Fabric data items, such as data warehouses and lakehouses, store their data automatically in OneLake.

Dremio creates connections to Microsoft OneLake using its Iceberg REST Catalog connector.

Configure a Microsoft OneLake Source

To add a Microsoft OneLake source connection:

1. On the Datasets page, to the right of Sources in the left panel, click .

2. In the Add Source dialog, under Lakehouse Catalogs, select Iceberg REST Catalog Source.

General

To configure the source connection:

1. For Name, enter a name for the source. The name you enter must be unique in the organization. Also, consider a name that is easy for users to reference. This name cannot be edited once the source is created. The name cannot exceed 255 characters and must contain only the following characters: 0-9, A-Z, a-z, underscore (_), or hyphen (-).
2. For Endpoint URI, specify the catalog service URI as https://onelake.table.fabric.microsoft.com/iceberg.
3. Clear Use vended credentials.
4. (Optional) For Allowed Namespaces, add each namespace and check the option if you want to include their entire subtrees. Tables are organized into namespaces, which can be at the top level or nested within one another. Namespace names cannot contain periods or spaces.

Advanced Options

Replace the placeholders inside <...> with your respective values. For example, a warehouse value could be icy/icelake.Lakehouse. The fs.* properties are used to establish connections to the storage underlying your catalog in OneLake.

1. Add the following Catalog Properties with their associated values.

   • rest.auth.type: oauth2
   • oauth2-server-uri: https://login.microsoftonline.com/<tenant_id>/oauth2/v2.0/token
   • scope: https://storage.azure.com/.default
   • warehouse: <catalog>
   • fs.azure.endpoint: dfs.fabric.microsoft.com
   • fs.azure.account.auth.type: OAuth
   • fs.azure.account.oauth2.client.endpoint: https://login.microsoftonline.com/<tenant_id>/oauth2/v2.0/token
   • fs.azure.account.oauth2.client.id: <oauth_client_id>

2. Add the following Catalog Credentials with their associated values:

   • fs.azure.account.oauth2.client.secret: <oauth_client_secret>
   • credential: <oauth_client_id:oauth_client_secret>

3. Under Cache Options, review the following table and edit the options to meet your needs.

   • Enable local caching when possible – Selected by default. Along with asynchronous access for cloud caching, local caching can improve query performance. See Cloud Columnar Cache for details.
   • Max percent of total available cache space to use when possible – Specifies the disk quota, as a percentage, that a source can use on any single executor node only when local caching is enabled. The default is 100 percent of the total disk space available on the mount point provided for caching. You can either manually enter a percentage in the value field or use the arrows to the far right to adjust the percentage.

Reflection Refresh

You can set the policy that controls how often reflections are scheduled to be refreshed automatically, as well as the time limit after which reflections expire and are removed. See the following options:

Option	Description
Never refresh	Select to prevent automatic reflection refresh. The default is to automatically refresh.
Refresh every	How often to refresh reflections, specified in hours, days, or weeks. This option is ignored if Never refresh is selected.
Set refresh schedule	Specify the daily or weekly schedule.
Never expire	Select to prevent reflections from expiring. The default is to automatically expire after the time limit below.
Expire after	The time limit after which reflections expire and are removed from Dremio, specified in hours, days, or weeks. This option is ignored if Never expire is selected.

Metadata

Metadata options are configured using the following settings.

Dataset Handling

• Remove dataset definitions if underlying data is unavailable (default).
• If this box is not checked and the underlying files under a folder are removed or the folder/source is not accessible, Dremio does not remove the dataset definitions. This option is useful in cases when files are temporarily deleted and put back in place with new sets of files.

Metadata Refresh

These are the optional Metadata Refresh parameters:

• Dataset Discovery: The refresh interval for fetching top-level source object names such as databases and tables. Set the time interval using this parameter.

  Parameter	Description
  Fetch every	You can set the frequency to fetch object names in minutes, hours, days, or weeks. The default frequency to fetch object names is 1 hour.

• Dataset Details: The metadata that Dremio needs for query planning, such as information needed for fields, types, shards, statistics, and locality. These are the parameters to fetch the dataset information.

  Parameter	Description
  Fetch mode	You can fetch only from queried datasets. Dremio updates details for previously queried objects in a source. By default, this is set to Only Queried Datasets.
  Fetch every	You can set the frequency to fetch dataset details in minutes, hours, days, or weeks. The default frequency to fetch dataset details is 1 hour.
  Expire after	You can set the expiry time of dataset details in minutes, hours, days, or weeks. The default expiry time of dataset details is 3 hours.

Privileges

You have the option to grant privileges to specific users or roles. See Access Control for additional information about privileges.

To grant access to a user or role:

1. For Privileges, enter the user name or role name to which you want to grant access and click the Add to Privileges button. The added user or role is displayed in the USERS/ROLES table.

2. For the users or roles in the USERS/ROLES table, toggle the checkmark for each privilege you want to grant on the Dremio source that is being created.

3. Click Save after setting the configuration.

Update a Microsoft OneLake Source

To update a Microsoft OneLake source connection:

1. On the Datasets page, under Lakehouse Catalogs in the panel on the left, find the name of the source you want to edit.
2. Right-click the source name and select Settings from the list of actions. Alternatively, click the source name and then the at the top right corner of the page.
3. In the Source Settings dialog, edit the settings you want to update. Dremio does not support updating the source name.
4. Click Save.

Delete a Microsoft OneLake Source

note

If the source is in a bad state (for example, Dremio cannot authenticate to the source or the source is otherwise unavailable), only users who belong to the ADMIN role can delete the source.

To delete a Microsoft OneLake source:

1. On the Datasets page, click Sources > Lakehouse Catalogs in the panel on the left.
2. In the list of data sources, hover over the name of the source you want to remove and right-click.
3. From the list of actions, click Delete.
4. In the Delete Source dialog, click Delete to confirm that you want to remove the source.

Deleting a source causes all downstream views that depend on objects in the source to break.