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.

• Ensure that you have an application (client) ID, directory (tenant) ID, and client secret for an Azure Active Directory application. You must provide Dremio with the IDs and secret to allow it to access the database.

  To register an Azure Active Directory application and obtain the IDs and client secret:

  1. Log into Azure portal and go to Azure Active Directory.
  2. Select App registrations on the left.
  3. Click New registration.
  4. Specify a name for the application.
  5. Select the single-tenant account type.
  6. Leave the Redirect URI field blank.
  7. Click Register in the bottom-left corner of the page.
  8. On the Overview page for the application, copy the application (client) ID and the directory (tenant) ID, and paste them in a location that you can refer to in a later step.
  9. Select Certificates & secrets on the left under Manage.
  10. Click New client secret.
  11. Specify a description of the secret and a duration of time for the secret to be valid for.
  12. Click Add.
  13. Copy the value of the secret and paste it in a location that you can refer to in a later step.

Configuring Azure Data Explorer as a Source

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

1. Click the Settings icon on the in the left navbar 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 and click Add Source in the bottom-left corner.
4. Under Databases in the Add Data Source dialog, select Microsoft Azure Data Explorer.

General Options

On the General page of the New Azure Data Explorer Source dialog, follow these steps:

1. Paste the cluster URI into the Cluster URI field.

2. Paste the directory (tenant) ID into the Tenant ID.

3. Paste the application (client) ID into the Application ID field.

4. Paste the client secret into the Application Secret field.

5. Specify the name of the database that you want to add as a source in the Database Name field.

:::note

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 page, you can grant privileges to specific users or roles. See Access Controls for additional information about user privileges.

1. (Optional) For Privileges, enter the user name or role name that you want to grant access to and click Add to Privileges. The added user or role is displayed in the Users table.
2. (Optional) For the users or roles in the Users table, toggle the green checkmark for each privilege you want to grant on the ADX source that is being created.

Click Save after setting the configuration.

Editing an ADX Source

To edit an ADX source:

1. In Dremio console, click Databases at the bottom-left of the page. A list of sources is displayed.

2. Click for the source you want to edit.

Alternatively, you can click the source and click of the source.

1. In the Source Settings dialog, you cannot edit the name. Editing other parameters is optional. For parameters and advanced options, see Configuring Azure Data Explorer as a Source.

2. Click Save.

Removing an ADX Source

To remove an ADX source, perform these steps:

1. In Dremio console, click Databases at the bottom-left of the page. A list of sources is displayed.

2. Click for the source that you want to remove.

3. From the list of actions, click Delete. Confirm that you want to remove the source.

   caution

   Removing a source causes all downstream views dependent on objects in this 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.