Microsoft Azure Data Explorer

You can add a source to Dremio that is a database in Azure Data Explorer (ADX).

Prerequisites

• Ensure that you have the URI for connecting to the ADX cluster in which the database is located.
• Ensure that you know the name of the database that you want to add as a source.

Configuring Azure Data Explorer as a Source

To add a database that is in an ADX cluster as a source in Dremio:

1. Click the Settings icon in the left navigation bar and select Support.
2. In the Support Keys section of the Support Settings page, add the support key plugins.jdbc.adx.enabledand toggle it on.
3. Navigate to the Datasets page. To the right of Sources in the left panel, click .
4. In the Add Data Source dialog, under Databases, select Microsoft Azure Data Explorer.

General

Under Name, enter the name to use for the Azure Data Explorer source. The name cannot include the following special characters: /, :, [, or ].

Connection

Describe the Data Explorer cluster used in this connection.

• Cluster URI: Enter the cluster URI.
• Tenant ID: Enter the directory (tenant) ID.

Authentication

Select an authentication option:

• Microsoft Entra ID: To register a Microsoft Entra ID application and obtain the required IDs and client secret, see How to register an app in Microsoft Entra ID, then complete the Dremio configuration:

  • Application ID: Enter the application (client) ID
  • Application Secret: Select the application secret store from the dropdown menu:
    • Dremio: Provide the application secret in plain text. Dremio stores the password.
    • Azure Key Vault: Provide the URI for your stored secret using the format https://<vault_name>.vault.azure.net/secrets/<secret_name>
    • AWS Secrets Manager: Provide the Amazon Resource Name (ARN) for the AWS Secrets Manager secret that holds the application secret, which is available in the AWS web console or using command line tools.
    • HashiCorp Vault: Select your HashiCorp secrets engine from the dropdown and enter the secret reference in the required format.

• Azure Managed Identity: Passwordless authentication using Azure's managed identity service, eliminating credential management overhead.

  1. Create a managed identity, system-assigned or user-assigned for your Data Explorer cluster.
  2. Attach the managed identity to your Dremio AKS cluster's Virtual Machine Scale Set (VMSS)
  3. Configure the Dremio source:
     • When using a user-assigned managed identity, add the Client ID to the Dremio source configuration.
     • When using a system-assigned managed identity, leave the Client ID blank.

• Under Database Name, enter the name of the database that you want to add as a source. Names are case-sensitive.

Advanced Options

On the Advanced Options page, you can set values for these non-required options:

Option	Description
Maximum Idle Connections	The total number of connections allowed to be idle at a given time. The default maximum idle connections is 8.
Connection Idle Time	The amount of time (in seconds) allowed for a connection to remain idle before the connection is terminated. The default connection idle time is 60 seconds.
Query Timeout	The amount of time (in seconds) allowed to wait for the results of a query. If this time expires, the connection being used is returned to an idle state.

Reflection Refresh Options

On the Reflection Refresh page, 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.

Option	Description
Never refresh	Select to prevent automatic Reflection refresh, 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.
Never expire	Select to prevent Reflections from expiring, 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 Options

On the Metadata page, you can configure settings to refresh metadata and handle datasets.

Dataset Handling

These are the optional Dataset Handling parameters.

Parameter	Description
Remove dataset definitions if underlying data is unavailable	By default, Dremio removes dataset definitions if underlying data is unavailable. Useful when files are temporarily deleted and added back in the same location 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
  (Optional) Fetch every	You can choose to 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 required for fields, types, shards, statistics, and locality. These are the parameters to fetch the dataset information.

  Parameter	Description
  Fetch mode	You can choose to fetch only from queried datasets that are set by default. Dremio updates details for previously queried objects in a source. Fetching from all datasets is deprecated.
  Fetch every	You can choose to 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 choose to set the expiry time of dataset details in minutes, hours, days, or weeks. The default expiry time of dataset details is 3 hours.

Privileges

On the Privileges tab, you can grant privileges to specific users or roles. See Access Controls for additional information about privileges. All privileges are optional.

1. For Privileges, enter the user name or role name that you want to grant access to 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.

Updating an ADX Source

To update an ADX source:

1. On the Datasets page, under Databases in the panel on the left, find the name of the source you want to update.
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 wish to update. Dremio does not support updating the source name. For information about the settings options, see Configuring Azure Data Explorer as a Source.
4. Click Save.

Deleting an ADX 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 an ADX source, perform these steps:

1. On the Datasets page, click Sources > Databases in the panel on the left.
2. In the list of data sources, hover over the name of the ADX source 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.

note

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

Query Pushdowns

Dremio can delegate the execution of these expressions and functions to the database being queried, often dramatically improving query performance.

-, =, +, *, /
<, <=, <>, >=, >, !=
ADD_MONTHS
AND, LIKE, NOT, OR, ||
AVG
CAST
CONCAT
COUNT *
COUNT DISTINCT
COUNT DISTINCT MULTI
COUNT MULTI
DATE_ADD
DATE_SUB
DATE_TRUNC_DAY
DATE_TRUNC_HOUR
DATE_TRUNC_MINUTE
DATE_TRUNC_MONTH
DATE_TRUNC_YEAR
FULL JOIN
INNER JOIN
IS DISTINCT FROM
IS NOT DISTINCT FROM
IS NOT NULL
IS NULL
JOIN
LAST_DAY
LEFT JOIN
MAX
MIN
MOD
RIGHT JOIN
SIGN
SORT
SUM

Running Queries Directly on Azure Data Explorer Through Dremio

Dremio users can run pass queries through Dremio to run on Azure Data Explorer. Doing so can sometimes decrease query execution times. For more information, see Querying Relational-Database Sources Directly.