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    Azure Data Explorer preview

    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:

    OptionDescription
    Maximum Idle ConnectionsThe total number of connections allowed to be idle at a given time. The default maximum idle connections is 8.
    Connection Idle TimeThe 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 TimeoutThe maximum amount of time to wait for queries to finish executing.

    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.

    OptionDescription
    Never refreshSelect to prevent automatic reflection refresh, default is to automatically refresh.
    Refresh everyHow often to refresh reflections, specified in hours, days or weeks. This option is ignored if Never refresh is selected.
    Never expireSelect to prevent reflections from expiring, default is to automatically expire after the time limit below.
    Expire afterThe 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.

    ParameterDescription
    Remove dataset definitions if underlying data is unavailableBy default, Dremio Cloud 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.

      ParameterDescription
      (Optional) Fetch everyYou 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 Cloud needs for query planning such as information required for fields, types, shards, statistics, and locality. These are the parameters to fetch the dataset information.

      ParameterDescription
      Fetch modeYou can choose to fetch only from queried datasets that are set by default. Dremio Cloud updates details for previously queried objects in a source. Fetching from all datasets is deprecated.
      Fetch everyYou 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 afterYou 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 the Add to Privileges button. 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 the Datasets UI, click External Sources at the bottom-left of the page. A list of sources is displayed.

    2. Under the Action column, click the Settings (gear) icon for the source you want to edit. From the list of actions, click Edit Details.

      Alternatively, you can click the source and click the Settings (gear) icon of the source.

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

    4. Click Save.

    Removing an ADX Source

    To remove an ADX source, perform these steps:

    1. In the Datasets UI, click External Sources at the bottom-left of the page. A list of sources is displayed.
    2. Under the Action column, click the Settings (gear) icon for the source that you want to remove.
    3. From the list of actions, click Remove Source. Confirm that you want to remove the source.

    warning:

    Removing a source causes all downstream virtual datasets dependent on objects in this source to break.

    Query Pushdowns

    Dremio delegates the execution of these expressions and functions to the database being queried, often dramatically improving query performance:

    ->count distinct multifull joinmax
    =>=count multiinner joinmin
    =+||date_addis distinct frommod
    !=anddate_subis not distinct fromnot
    *avgdate_trunc_dayis not nullor
    /castdate_trunc_houris nullright join
    <concatdate_trunc_minutejoinsign
    <=count *date_trunc_monthleft joinsort
    <>count distinctdate_trunc_yearlikesum