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Databricks Labs UCX

UCX by Databricks Labs

The companion for upgrading to Unity Catalog (UC).

After installation, ensure to trigger the assessment workflow, so that you'll be able to scope the migration and execute the group migration workflow.

The README notebook, which can be found in the installation folder contains further instructions and explanations of the different ucx workflows & dashboards. Once the migration is scoped, you can start with the table migration process.

More workflows, like notebook code migration are coming in future releases.

UCX also provides a number of command line utilities accessible via databricks labs ucx.

For questions, troubleshooting or bug fixes, please see our troubleshooting guide or submit an issue. See contributing instructions to help improve this project.

build codecov linesofcode

Installation

UCX installation is covered by this section.

Installation requirements

UCX has the following installation requirements:

  • Databricks CLI v0.213 or later. See instructions.
  • Python 3.10 or later. See Windows instructions.
  • Databricks Premium or Enterprise workspace.
  • Network access to your Databricks Workspace used for the installation process.
  • Network access to the Internet for pypi.org and github.com from machine running the installation.
  • Databricks Workspace Administrator privileges for the user, that runs the installation. Running UCX as a Service Principal is not supported.
  • Account level Identity Setup. See instructions for AWS, Azure, and GCP.
  • Unity Catalog Metastore Created (per region). See instructions for AWS, Azure, and GCP.
  • If your Databricks Workspace relies on an external Hive Metastore (such as AWS Glue), make sure to read this guide.
  • A PRO or Serverless SQL Warehouse to render the report for the assessment workflow.

Once you install UCX, you can proceed to the assessment workflow to ensure the compatibility of your workspace with Unity Catalog.

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Authenticate Databricks CLI

We only support installations and upgrades through Databricks CLI, as UCX requires an installation script run to make sure all the necessary and correct configurations are in place. Install Databricks CLI on macOS: macos_install_databricks

Install Databricks CLI on Windows: windows_install_databricks.png

Once you install Databricks CLI, authenticate your current machine to a Databricks Workspace:

databricks auth login --host WORKSPACE_HOST

To enable debug logs, simply add --debug flag to any command.

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Install UCX

Install UCX via Databricks CLI:

databricks labs install ucx

You'll be prompted to select a configuration profile created by databricks auth login command.

Once you install, proceed to the assessment workflow to ensure the compatibility of your workspace with UCX.

The WorkspaceInstaller class is used to create a new configuration for Unity Catalog migration in a Databricks workspace. It guides the user through a series of prompts to gather necessary information, such as selecting an inventory database, choosing a PRO or SERVERLESS SQL warehouse, specifying a log level and number of threads, and setting up an external Hive Metastore if necessary. Upon the first installation, you're prompted for a workspace local group migration strategy. Based on user input, the class creates a new cluster policy with the specified configuration. The user can review and confirm the configuration, which is saved to the workspace and can be opened in a web browser.

The WorkspaceInstallation manages the installation and uninstallation of UCX in a workspace. It handles the configuration and exception management during the installation process. The installation process creates dashboards, databases, and jobs. It also includes the creation of a database with given configuration and the deployment of workflows with specific settings. The installation process can handle exceptions and infer errors from job runs and task runs. The workspace installation uploads wheels, creates cluster policies, and wheel runners to the workspace. It can also handle the creation of job tasks for a given task, such as job dashboard tasks, job notebook tasks, and job wheel tasks. The class handles the installation of UCX, including configuring the workspace, installing necessary libraries, and verifying the installation, making it easier for users to migrate their workspaces to UCX. At the end of the installation, the user will be prompted if the current installation needs to join an existing collection (create new collection if none present). For large organization with many workspaces, grouping workspaces into collection helps in managing UCX migration at collection level (instead of workspaces level) User should be an account admin to be able to join a collection.

After this, UCX will be installed locally and a number of assets will be deployed in the selected workspace. These assets are available under the installation folder, i.e. /Applications/ucx is the default installation folder. Please check here for more details.

You can also install a specific version by specifying it like @v0.13.2 - databricks labs install ucx@v0.13.2.

macos_install_ucx

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Installation resources

The following resources are installed by UCX:

Installed UCX resources Description
Inventory database A Hive metastore database/schema in which UCX persist inventory required for the upgrade process
Workflows Workflows to execute UCX
Dashboards Dashboards to visualize UCX outcomes
Installation folder A workspace folder containing UCX files in /Applications/ucx/.

Installation folder

UCX is in installed in the workspace folder /Applications/ucx/. This folder contains UCX's code resources, like the source code from this GitHub repository and the dashboard. Generally, these resources are not directly used by UCX users. Resources that can be of importance to users are detailed in the subsections below.

Readme notebook

readme

Every installation creates a README notebook with a detailed description of all deployed workflows and their tasks, providing quick links to the relevant workflows and dashboards.

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Debug notebook

debug

Every installation creates a DEBUG notebook, that initializes UCX as a library for you to execute interactively.

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Debug logs

debug

The workflow runs store debug logs in the logs folder of the installation folder. The logs are flushed every minute in a separate file. Debug logs for the command-line interface are shown by adding the --debug flag:

databricks --debug labs ucx <command>

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Installation configuration

In the installation folder, the UCX configuration is kept.

Advanced installation options

Advanced installation options are detailed below.

Force install over existing UCX

Using an environment variable UCX_FORCE_INSTALL you can force the installation of UCX over an existing installation. The values for the environment variable are 'global' and 'user'.

Global Install: When UCX is installed at '/Applications/ucx' User Install: When UCX is installed at '/Users//.ucx'

If there is an existing global installation of UCX, you can force a user installation of UCX over the existing installation by setting the environment variable UCX_FORCE_INSTALL to 'global'.

At this moment there is no global override over a user installation of UCX. As this requires migration and can break existing installations.

global user expected install location install_folder mode
no no default /Applications/ucx install
yes no default /Applications/ucx upgrade
no yes default /Users/X/.ucx upgrade (existing installations must not break)
yes yes default /Users/X/.ucx upgrade
yes no USER /Users/X/.ucx install (show prompt)
no yes GLOBAL ... migrate
  • UCX_FORCE_INSTALL=user databricks labs install ucx - will force the installation to be for user only
  • UCX_FORCE_INSTALL=global databricks labs install ucx - will force the installation to be for root only

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Installing UCX on all workspaces within a Databricks account

Setting the environment variable UCX_FORCE_INSTALL to 'account' will install UCX on all workspaces within a Databricks account.

  • UCX_FORCE_INSTALL=account databricks labs install ucx

After the first installation, UCX will prompt the user to confirm whether to install UCX on the remaining workspaces with the same answers. If confirmed, the remaining installations will be completed silently.

This installation mode will automatically select the following options:

  • Automatically create and enable HMS lineage init script
  • Automatically create a new SQL warehouse for UCX assessment

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Installing UCX with company hosted PYPI mirror

Some enterprise block the public PYPI index and host a company controlled PYPI mirror. To install UCX while using a company hosted PYPI mirror for finding its dependencies, add all UCX dependencies to the company hosted PYPI mirror (see "dependencies" in pyproject.toml) and set the environment variable PIP_INDEX_URL to the company hosted PYPI mirror URL while installing UCX:

PIP_INDEX_URL="https://url-to-company-hosted-pypi.internal" databricks labs install ucx

During installation reply yes to the question "Does the given workspace block Internet access"?

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Upgrading UCX for newer versions

Verify that UCX is installed

databricks labs installed

Name  Description                            Version
ucx   Unity Catalog Migration Toolkit (UCX)  <version>

Upgrade UCX via Databricks CLI:

databricks labs upgrade ucx

The prompts will be similar to Installation

macos_upgrade_ucx

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Uninstall UCX

Uninstall UCX via Databricks CLI:

databricks labs uninstall ucx

Databricks CLI will confirm a few options:

  • Whether you want to remove all ucx artefacts from the workspace as well. Defaults to no.
  • Whether you want to delete the inventory database in hive_metastore. Defaults to no.

macos_uninstall_ucx

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Migration process

On a high level, the steps in migration process are:

  1. assessment
  2. group migration
  3. table migration
  4. data reconciliation
  5. code migration

The migration process can be schematic visualized as:

flowchart TD
    subgraph workspace-admin
        assessment --> group-migration
        group-migration --> table-migration
        table-migration --> code-migration
        assessment --> create-table-mapping
        create-table-mapping --> table-migration
        create-table-mapping --> code-migration
        validate-external-locations --> table-migration
        assessment --> validate-table-locations
        validate-table-locations --> table-migration
        table-migration --> revert-migrated-tables
        revert-migrated-tables --> table-migration
    end
    subgraph account-admin
        create-account-groups --> group-migration
        sync-workspace-info --> create-table-mapping
        group-migration --> validate-groups-membership
    end
    subgraph iam-admin
        setup-account-scim --> create-account-groups
        assessment --> create-uber-principal
        create-uber-principal --> table-migration
        assessment --> principal-prefix-access
        principal-prefix-access --> migrate-credentials
        migrate-credentials --> validate-external-locations
        setup-account-scim
    end
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Table migration process

You are required to complete the assessment workflow before starting the table migration workflow.

This section explains how to migrate Hive metastore data objects to Unity Catalog. The table migration process consists of more steps than only a workflow, these steps are:

  1. Table mapping : Create a file that maps Hive metastore data objects to Unity Catalog locations.
  2. Data access : Setup identities to access table data.
  3. New Unity Catalog resources : Create new Unity Catalog resources that do not require touching existing Hive metastore resources.
  4. Migrate Hive metastore data objects : Migrate Hive metastore data objects to UC.

Table mapping

This section details how to create the table mapping file. This file points existing Hive metastore tables and views to Unity Catalog locations. When migrating the tables and views, the file is read to decide where to migrate the tables and views to.

Step 1 : Create the mapping file

Create the mapping file in the UCX installation folder by running the create-table-mapping command. By default, the file contains all the Hive metastore tables and views mapped to a single UC catalog, while maintaining the original schema and table names.

Step 2: Update the mapping file

Edit the mapping file from the previous step to:

  • Exclude tables and/or views by removing the lines
  • Change UC location by editing the destination catalog and/or schema

The mapping file is in CSV format and can be edited using any text editor or Excel. If using Excel, save the file in CSV format.

Example changes:

Before editing

workspace_name catalog_name src_schema dst_schema src_table dst_table
data_engineering_ws 123333333 sales_analysis sales_analysis ytd_sales ytd_sales

After editing

workspace_name catalog_name src_schema dst_schema src_table dst_table
data_engineering_ws data_engineering sales_analysis sales ytd_sales ytd_analysis

Data access

Throughout this guide, we refer to IAM roles/instance profiles in AWS & service principals/managed identities in as "cloud principals".

This section creates the cloud principals to access data in Unity Catalog and during the table data during migration. To understand the motivation for this step, read how Databricks accesses cloud locations:

Step 1 : Map cloud principals to cloud storage locations

Map the cloud principals to cloud storage by running the principal-prefix-access command.

Step 2 : Create or modify cloud principals and credentials

Manually create the cloud principals to access data from Unity Catalog:

Then, run the migrate-credentials command to migrate the cloud principal credentials to Unity Catalog.

Step 3: Create the "uber" Principal

Create the "uber" principal by running the create-uber-principal command. The table migration requires a cloud principal with access to table data stored in cloud storage. These tables are known as external tables. UCX name this cloud principal the "uber" principal as it has access to all in-scope cloud storage. This principal is only required for the table migration process and not for ongoing UC usage. Once the upgrade is completed, this principal should be deleted.

New Unity Catalog resources

This section details the new Unity Catalog resources required for migration the data objects. These resources can be created without touching the existing Hive metastore objecs.

Step 0: Attach a metastore

If skipping the group migration, then a metastore should be attached to the workspace by following these instructions or running the assign-metastore command.

Step 1: Create external Locations

Create UC external locations by running the migration-locations command. The command creates a location for each location found during the assessment. It uses the credentials created in the previous steps.

Alternatively, manually create the external locations

Step 2: Create Catalogs and Schemas

Create Uniyt Catalog catalogs and schemas to organize the destination tables and views in by running the create-catalogs-schemas command. The command creates the UC catalogs and schemas based on the table mapping file. Additionally, it migrates Hive metastore database permissions if present.

This step requires considering how to physically separate data in storage within UC. As Databricks recommends storing managed data at the catalog level, we advise to prepare the external locations for the to-be created catalogs before running the create-catalogs-schemas command. Either, reuse previously created external locations or create additional external locations outside of UCX if data separation restrictions requires that. Note that external locations can be reused when using subpaths, for example, a folder in a cloud storage (abfss://container@storage.dfs.core.windows.net/folder) can reuse the external location of the cloud storage (abfss://container@storage.dfs.core.windows.net/). (The previous example also holds for other clouds.)

Migrate Hive metastore data objects

In this step, tables and views are migrated using the following workflows:

flowchart LR
    subgraph CLI
        migrate-tables[migrate-tables]
    end

    subgraph mt_workflow[workflow: migrate-tables]
        dbfs_root_delta_mt_task[migrate_dbfs_root_delta_tables]
        migrate_dbfs_root_non_delta_tables[migrate_dbfs_root_non_delta_tables]
        external_tables_sync_mt_task[migrate_external_tables_sync]
        view_mt_task[migrate_views]
        refresh_migration_status[refresh_migration_status]
        external_tables_sync_mt_task --> view_mt_task
        dbfs_root_delta_mt_task --> view_mt_task
        migrate_dbfs_root_non_delta_tables --> view_mt_task
        view_mt_task --> refresh_migration_status
    end

    subgraph mt_serde_inplace_wf[workflow: migrate-external-hiveserde-tables-in-place-experimental]
        serde_inplace_mt_task[migrate_hive_serde_in_place] --> view_mt_task_inplace[migrate_views]
        view_mt_task_inplace --> refresh_migration_status_hiveserde[refresh_migration_status]
    end

    subgraph mt_ctas_wf[workflow: migrate-external-tables-ctas]
        ctas_mt_task[migrate_other_external_ctas]
        migrate_hive_serde_ctas[migrate_hive_serde_ctas]
        view_mt_ctas_task[migrate_views]
        refresh_migration_status_ctas[refresh_migration_status]
        ctas_mt_task --> view_mt_ctas_task
        migrate_hive_serde_ctas --> view_mt_ctas_task
        view_mt_ctas_task --> refresh_migration_status_ctas
    end

    migrate-tables -- 1st --> mt_workflow
    migrate-tables -- 2nd (optional) table migrated here will be excluded in ctas workflow --> mt_serde_inplace_wf
    migrate-tables -- 3rd --> mt_ctas_wf
Loading

The table migration workflows can be triggered using the migrate-tables command or by starting the workflows from the workspace UI manually. The table migration workflows are designed to minimize data copying and to maintain metadata while allowing users to choose preferred strategies where possible. Chose the strategies for migrating tables using the table below:

Object Type Description Upgrade Method
DBFS_ROOT_DELTA Delta tables persisted on the Databricks file system (dbfs). Create a copy of the table with the DEEP CLONE command.
DBFS_ROOT_NON_DELTA Non-delta tables persisted on the Databricks file system (dbfs). Create a copy of the table with a CREATE TABLE AS SELECT * FROM command. The UC table will be a Delta table.
MANAGED Managed Hive metastore tables. Depending on the managed table migration strategy chosen during installation:
1. CLONE: Create a copy of the table with a CREATE TABLE LOCATION '<location>' AS SELECT * FROM command.
2. SYNC_AS_EXTERNAL, synchronize the table metadata to UC with the SYNC command. Warning: If the managed Hive metastore table is dropped, the drop deletes the underlying data affecting the synchronised UC table as well.
3. CONVERT_TO_EXTERNAL: First, in-place convert the managed Hive metastore to a non-managed table. Then, synchronize the table metadata to UC with the SYNC command. Warning: This strategy has the advantage over SYNC_AS_EXTERNAL that dropping the Hive metastore table does not delete the underlying data, however, impact should be carefully validated in existing workloads as the strategy converts the managed Hive metastore to an external table in-place.
EXTERNAL_SYNC External tables that the SYNC command supports: Delta, Parquet, CSV, JSON, ORC, text or Avro tables. Synchronize the table metadata to UC with the SYNC command.
EXTERNAL_NO_SYNC External tables that the SYNC command does not support. Create a copy of the table with a CREATE TABLE AS SELECT * FROM command. The UC table will be a Delta table.
EXTERNAL_HIVESERDE External Hive SerDe tables that the SYNC command does not support. Depending on the migration workflow chosen:
1. migrate-external-tables-ctas (officially supported) : Create a copy of the table with a CREATE TABLE AS SELECT * FROM command The UC table will be a Delta table.
2. migrate-external-hiveserde-tables-in-place-experimental (experimental) : Recreate the Hive SerDe tables using the serialization and deserialization protocols. Warning: Although this strategy is supported, there is a risk that the old files created by Hive SerDe may not be processed correctly by Spark datasource in corner cases.
VIEW Views Recreate views using their definitions after repointing their dependencies to UC objects. The migration process supports views depending on other views.

The workflows may be executed multiple times. Each step is designed as a standalone operation that migrates all in-scope tables. After migration, each object is marked with an upgraded_to property containing the UC identifier to which the object is migrated. This property signals that the object is out-of-scope for other migration operations and that the view dependency exists within UC. The created UC objects are marked with an upgraded_from property containing the Hive metastore identifier from which the object was migrated.

Finally, the table migration workflows also migrate Hive metastore permissions to Unity Catalog.

Considerations:

  • You may want to run the workflows multiple times to migrate tables in phases.
  • If your Delta tables in DBFS root have a large number of files, consider:
    • Setting higher Min and Max workers for auto-scale when being asked during the UCX installation. More cores in the cluster means more concurrency for calling cloud storage API to copy files when deep cloning the Delta tables.
    • Setting higher Parallelism for migrating DBFS root Delta tables with deep clone (default 200) when being asked during the UCX installation. This controls the number of Spark tasks/partitions to be created for deep clone.
  • Consider creating an instance pool, and setting its id when prompted during the UCX installation. This instance pool will be specified in the cluster policy used by all UCX workflows job clusters.
  • You may also manually edit the job cluster configration per job or per task after the workflows are deployed.

Additional references:

Odds and Ends

The following sections detail how to repair/amend the UC metastore after the upgrade process.

Skip migrating schemas, tables or views

databricks labs ucx skip --schema X [--table Y] [--view Zj]

The skip command marks a schema, table or view as to-be skipped during the migration processes.

Move data objects

databricks labs ucx move --from-catalog A --from-schema B --from-table C --to-catalog D --to-schema E

The move command moves the object from the source to the target location. The upgraded_from property are updated to reflect the new location on the source object. Use this command if the data object is migrated to the wrong destination.

Alias data objects

databricks labs ucx alias --from-catalog A --from-schema B --from-table C --to-catalog D --to-schema E

This alias command creates an alias for the object in the target location by creating a view reading from the table that needs aliasing. It will create a mirror view to view that is marked as alias. Use this command if Hive metastore tables point to the same location as UC does not support UC does not support tables with overlapping data locations.

Revert migrated data objects

databricks labs ucx revert-migrated-tables --schema X --table Y [--delete-managed]

The revert-migrated-tables command drops the Unity Catalog table or view and reset the upgraded_to property on the source object. Use this command to allow for migrating a table or view again.

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Workflows

Part of this application is deployed as Databricks Workflows. You can view the status of deployed workflows via the workflows command. Failed workflows can be fixed with the repair-run command.

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Assessment workflow

ucx_assessment_workflow

The assessment workflow can be triggered using the Databricks UI or via the ensure-assessment-run command.

The assessment workflow retrieves - or crawls - details of workspace assets and securable objects in the Hive metastore relevant for upgrading to UC to assess the compatibility with UC. The crawl_ tasks retrieve assess and objects. The assess_ tasks assess the compatibility with UC. The output of each task is stored in the inventory database so that it can be used for further analysis and decision-making through the assessment report.

  1. crawl_tables: This task retrieves table definitions from the Hive metastore and persists the definitions in the tables table. The definitions include information such as:
    • Database/schema name
    • Table name
    • Table type
    • Table location
  2. crawl_udfs: This task retrieves UDF definitions from the Hive metastore and persists the definitions in the udfs table.
  3. setup_tacl: (Optimization) This task starts the tacl job cluster in parallel to other tasks.
  4. crawl_grants: This task retrieves privileges you can grant on Hive objects and persists the privilege definitions in the grants table The retrieved permission definitions include information such as:
    • Securable object: schema, table, view, (anonymous) function or any file.
    • Principal: user, service principal or group
    • Action type: grant, revoke or deny
  5. estimate_table_size_for_migration: This task analyzes the Delta table retrieved by crawl_tables to retrieve an estimate of their size and persists the table sizes in the table_size table. The table size support the decision for using the SYNC or CLONE table migration strategy.
  6. crawl_mounts: This task retrieves mount point definitions and persists the definitions in the mounts table.
  7. guess_external_locations: This task guesses shared mount path prefixes of external tables retrieved by crawl_tables that use mount points and persists the locations in the external_locations table. The goal is to identify the to-be created UC external locations.
  8. assess_jobs: This task retrieves the job definitions and persists the definitions in the jobs table. Job definitions may require updating to become UC compatible.
  9. assess_clusters: This task retrieves the clusters definitions and persists the definitions in the clusters table. Cluster definitions may require updating to become UC compatible.
  10. assess_pipelines: This task retrieves the Delta Live Tables (DLT) pipelines definitions and persists the definitions in the pipelines table. DLT definitions may require updating to become UC compatible.
  11. assess_incompatible_submit_runs : This task retrieves job runs, also known as job submit runs, and persists the definitions in the submit_runs table. Incompatibility with UC is assessed:
  12. crawl_cluster_policies : This tasks retrieves cluster policies and persists the policies in the policies table. Incompatibility with UC is assessed:
  13. assess_azure_service_principals: This tasks retrieves Azure service principal authentications information from Spark configurations to access storage accounts and persists these configuration information in azure_service_principals table. The Spark configurations from the following places are retrieved:
    • Clusters configurations
    • Cluster policies
    • Job cluster configurations
    • Pipeline configurations
    • Warehouse configuration
  14. assess_global_init_scripts: This task retrieves global init scripts and persists references to the scripts in the global_init_scripts table. Again, Azure service principal authentication information might be given in those scripts.
  15. workspace_listing : This tasks lists workspace files recursively to compile a collection of directories, notebooks, files, repos and libraries. The task uses multi-threading to parallelize the listing process for speeding up execution on big workspaces.
  16. crawl_permissions : This tasks retrieves workspace-local groups permissions and persists these permissions in the permissions table.
  17. crawl_groups: This tasks retrieves workspace-local groups and persists these permissions in the groups table.
  18. assess_dashboards: This task retrieves the dashboards to analyze their queries for migration problems
  19. assess_workflows: This task retrieves the jobs to analyze their notebooks and files for migration problems.

After UCX assessment workflow finished, see the assessment dashboard for findings and recommendations. See this guide for more details.

report

Proceed to the group migration workflow below or go back to the migration process diagram.

The UCX assessment workflow is designed to only run once, re-running will not update the existing results. If the inventory and findings for a workspace need to be updated then first reinstall UCX by uninstalling and installing it again.

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Group migration workflow

You are required to complete the assessment workflow before starting the group migration workflow.

The group migration workflow does NOT CREATE account groups. In contrast to account groups, the (legacy) workspace-local groups cannot be assigned to additional workspaces or granted access to data in a Unity Catalog metastore. A Databricks admin assigns account groups to workspaces using identity federation to manage groups from a single place: your Databricks account. We expect UCX users to create account groups centrally while most other Databricks resources that UCX touches are scoped to a single workspace. If you do not have account groups matching the workspace in which UCX is installed, please run create-account-groups command before running the group migration workflow.

The group migration workflow is designed to migrate workspace-local groups to account-level groups. It verifies if the necessary groups are available to the workspace with the correct permissions, and removes unnecessary groups and permissions. The group migration workflow depends on the output of the assessment workflow, thus, should only be executed after a successful run of the assessment workflow. The group migration workflow may be executed multiple times.

  1. verify_metastore_attached: Verifies if a metastore is attached. Account level groups are only available when a metastore is attached. See assign-metastore command.
  2. rename_workspace_local_groups: This task renames workspace-local groups by adding a ucx-renamed- prefix. This step is taken to avoid conflicts with account groups that may have the same name as workspace-local groups.
  3. reflect_account_groups_on_workspace: This task adds matching account groups to this workspace. The matching account groups must exist for this step to be successful. This step is necessary to ensure that the account groups are available in the workspace for assigning permissions.
  4. apply_permissions_to_account_groups: This task assigns the full set of permissions of the original group to the account-level one. This step is necessary to ensure that the account-level groups have the necessary permissions to manage the entities in the workspace. It covers workspace-local permissions for all entities including:
    • Legacy Table ACLs
    • Entitlements
    • AWS instance profiles
    • Clusters
    • Cluster policies
    • Instance Pools
    • Databricks SQL warehouses
    • Delta Live Tables
    • Jobs
    • MLflow experiments
    • MLflow registry
    • SQL Dashboards & Queries
    • SQL Alerts
    • Token and Password usage permissions
    • Secret Scopes
    • Notebooks
    • Directories
    • Repos
    • Files
  5. validate_groups_permissions: This task validates that all the crawled permissions are applied correctly to the destination groups.

After successfully running the group migration workflow:

  1. Use validate-groups-membership command for extra confidence the newly created account level groups are considered to be valid.
  2. Run the remove-workspace-local-backup-grups to remove workspace-level backup groups, along with their permissions. This should only be executed after confirming that the workspace-local migration worked successfully for all the groups involved. This step is necessary to clean up the workspace and remove any unnecessary groups and permissions.
  3. Proceed to the table migration process.

For additional information see:

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Table migration workflows

This section lists the workflows that migrate tables and views. See this section for deciding which workflow to run and additional context for migrating tables.

Migrate tables

The general table migration workflow migrate-tables migrates all tables and views using default strategies.

  1. migrate_external_tables_sync : This step migrates the external tables that are supported by SYNC command.
  2. migrate_dbfs_root_delta_tables : This step migrates delta tables stored in DBFS root using the DEEP CLONE command.
  3. migrate_dbfs_root_non_delta_tables : This step migrates non-delta tables stored in DBFS root using the CREATE TABLE AS SELECT * FROM command.
  4. migrate_views : This step migrates views using the CREATE VIEW command.
  5. update_migration_status : Refresh the migration status of all data objects.

Migrate external Hive SerDe tables

The experimental table migration workflow migrate-external-hiveserde-tables-in-place-experimental migrates tables that support the SYNC AS EXTERNAL command.

  1. migrate_hive_serde_in_place : This step migrates the Hive SerDe tables that are supported by SYNC AS EXTERNAL command.
  2. migrate_views : This step migrates views using the CREATE VIEW command.
  3. update_migration_status : Refresh the migration status of all data objects.

Migrate external tables CTAS

The table migration workflow migrate-external-tables-ctas migrates tables with the CREATE TABLE AS SELECT * FROM command.

  1. migrate_other_external_ctas This step migrates the Hive Serde tables using the CREATE TABLE AS SELECT * FROM command.
  2. migrate_hive_serde_ctas : This step migrates the Hive Serde tables using the CREATE TABLE AS SELECT * FROM command.
  3. migrate_views : This step migrates views using the CREATE VIEW command.
  4. update_migration_status : Refresh the migration status of all data objects.

Post-migration data reconciliation workflow

The migrate-data-reconciliation workflow validates the integrity of the migrated tables and persists its results in the recon_results table. The workflow compares the following between the migrated Hive metastore and its UC counterpart table:

  • Schema : See this result in the schema_matches column.
  • Column by column : See this result in the column_comparison column.
  • Row counts : If the row count is within the reconciliation threshold (defaults to 5%), the data_matches column is set to true, otherwise it is set to false.
  • Rows : If the compare_rows flag is set to true, rows are compared using a hash comparison. Number of missing rows are stored in the source_missing_count and target_missing_count column, respectively.

The output is processed and displayed in the migration dashboard using the in reconciliation_results view.

reconciliation results

[LEGACY] Scan tables in mounts Workflow

Always run this workflow AFTER the assessment has finished

  • This experimental workflow attempts to find all Tables inside mount points that are present on your workspace.
  • If you do not run this workflow, then migrate-tables-in-mounts-experimental won't do anything.
  • It writes all results to hive_metastore.<inventory_database>.tables, you can query those tables found by filtering on database values that starts with mounted_
  • This command is incremental, meaning that each time you run it, it will overwrite the previous tables in mounts found.
  • Current format are supported:
    • DELTA - PARQUET - CSV - JSON
    • Also detects partitioned DELTA and PARQUET
  • You can configure these workflows with the following options available on conf.yml:
    • include_mounts : A list of mount points to scans, by default the workflow scans for all mount points
    • exclude_paths_in_mount : A list of paths to exclude in all mount points
    • include_paths_in_mount : A list of paths to include in all mount points

[LEGACY] Migrate tables in mounts Workflow

  • An experimental workflow that migrates tables in mount points using a CREATE TABLE command, optinally sets a default tables owner if provided in default_table_owner conf parameter.
  • You must do the following in order to make this work:

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[EXPERIMENTAL] Migration Progress Workflow

The manually triggered migration-progress-experimental workflow populates the tables visualized in the migration progress dashboard by updating a subset of the inventory tables to track Unity Catalog compatability of Hive and workspace objects that need to be migrated.

The following pre-requisites need to be fulfilled before running the workflow:

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Dashboards

The dashboards visualize UCX's outcomes. Each dashboard has text widgets detailing the contents in more detail. Below an overview with a short description is given.

Name Description
Assessment [Main] Assessment overview
Assessment [Estimates] Migration effort estimates based on the assessment
Assessment [Interactive] Assessment outcomes on interactive clusters
Assessment [Azure] Assessment outcomes specific to Azure
Migration [Main] Migration overview
Migration [Groups] Group migration outcomes
Progress [Main] Migration progress

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Linter message codes

code compatibility problems

Here's the detailed explanation of the linter message codes:

cannot-autofix-table-reference

This indicates that the linter has found a table reference that cannot be automatically fixed. The user must manually update the table reference to point to the correct table in Unity Catalog. This mostly occurs, when table name is computed dynamically, and it's too complex for our static code analysis to detect it. We detect this problem anywhere where table name could be used: spark.sql, spark.catalog.*, spark.table, df.write.* and many more. Code examples that trigger this problem:

spark.table(f"foo_{some_table_name}")
# ..
df = spark.range(10)
df.write.saveAsTable(f"foo_{some_table_name}")
# .. or even
df.write.insertInto(f"foo_{some_table_name}")

Here the some_table_name variable is not defined anywhere in the visible scope. Though, the analyser would successfully detect table name if it is defined:

some_table_name = 'bar'
spark.table(f"foo_{some_table_name}")

We even detect string constants when coming either from dbutils.widgets.get (via job named parameters) or through loop variables. If old.things table is migrated to brand.new.stuff in Unity Catalog, the following code will trigger two messages: table-migrated-to-uc for the first query, as the contents are clearly analysable, and cannot-autofix-table-reference for the second query.

# ucx[table-migrated-to-uc:+4:4:+4:20] Table old.things is migrated to brand.new.stuff in Unity Catalog
# ucx[cannot-autofix-table-reference:+3:4:+3:20] Can't migrate table_name argument in 'spark.sql(query)' because its value cannot be computed
table_name = f"table_{index}"
for query in ["SELECT * FROM old.things", f"SELECT * FROM {table_name}"]:
    spark.sql(query).collect()

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catalog-api-in-shared-clusters

spark.catalog.* functions require Databricks Runtime 14.3 LTS or above on Unity Catalog clusters in Shared access mode, so of your code has spark.catalog.tableExists("table") or spark.catalog.listDatabases(), you need to ensure that your cluster is running the correct runtime version and data security mode.

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changed-result-format-in-uc

Calls to these functions would return a list of <catalog>.<database>.<table> instead of <database>.<table>. So if you have code like this:

for table in spark.catalog.listTables():
    do_stuff_with_table(table)

you need to make sure that do_stuff_with_table can handle the new format.

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direct-filesystem-access-in-sql-query

Direct filesystem access is deprecated in Unity Catalog. DBFS is no longer supported, so if you have code like this:

df = spark.sql("SELECT * FROM parquet.`/mnt/foo/path/to/parquet.file`")

you need to change it to use UC tables.

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direct-filesystem-access

Direct filesystem access is deprecated in Unity Catalog. DBFS is no longer supported, so if you have code like this:

display(spark.read.csv('/mnt/things/data.csv'))

or this:

display(spark.read.csv('s3://bucket/folder/data.csv'))

You need to change it to use UC tables or UC volumes.

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dependency-not-found

This message indicates that the linter has found a dependency, like Python source file or a notebook, that is not available in the workspace. The user must ensure that the dependency is available in the workspace. This usually means an error in the user code.

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jvm-access-in-shared-clusters

You cannot access Spark Driver JVM on Unity Catalog clusters in Shared Access mode. If you have code like this:

spark._jspark._jvm.com.my.custom.Name()

or like this:

log4jLogger = sc._jvm.org.apache.log4j
LOGGER = log4jLogger.LogManager.getLogger(__name__)

you need to change it to use Python equivalents.

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legacy-context-in-shared-clusters

SparkContext (sc) is not supported on Unity Catalog clusters in Shared access mode. Rewrite it using SparkSession (spark). Example code that triggers this message:

df = spark.createDataFrame(sc.emptyRDD(), schema)

or this:

sc.parallelize([1, 2, 3])

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not-supported

Installing eggs is no longer supported on Databricks 14.0 or higher.

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notebook-run-cannot-compute-value

Path for dbutils.notebook.run cannot be computed and requires adjusting the notebook path. It is not clear for automated code analysis where the notebook is located, so you need to simplify the code like:

b = some_function()
dbutils.notebook.run(b)

to something like this:

a = "./leaf1.py"
dbutils.notebook.run(a)

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python-udf-in-shared-clusters

applyInPandas requires DBR 14.3 LTS or above on Unity Catalog clusters in Shared access mode. Example:

df.groupby("id").applyInPandas(subtract_mean, schema="id long, v double").show()

Arrow UDFs require DBR 14.3 LTS or above on Unity Catalog clusters in Shared access mode.

@udf(returnType='int', useArrow=True)
def arrow_slen(s):
    return len(s)

It is not possible to register Java UDF from Python code on Unity Catalog clusters in Shared access mode. Use a %scala cell to register the Scala UDF using spark.udf.register. Example code that triggers this message:

spark.udf.registerJavaFunction("func", "org.example.func", IntegerType())

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rdd-in-shared-clusters

RDD APIs are not supported on Unity Catalog clusters in Shared access mode. Use mapInArrow() or Pandas UDFs instead.

df.rdd.mapPartitions(myUdf)

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spark-logging-in-shared-clusters

Cannot set Spark log level directly from code on Unity Catalog clusters in Shared access mode. Remove the call and set the cluster spark conf spark.log.level instead:

sc.setLogLevel("INFO")
setLogLevel("WARN")

Another example could be:

log4jLogger = sc._jvm.org.apache.log4j
LOGGER = log4jLogger.LogManager.getLogger(__name__)

or

sc._jvm.org.apache.log4j.LogManager.getLogger(__name__).info("test")

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sql-parse-error

This is a generic message indicating that the SQL query could not be parsed. The user must manually check the SQL query.

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sys-path-cannot-compute-value

Path for sys.path.append cannot be computed and requires adjusting the path. It is not clear for automated code analysis where the path is located.

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table-migrated-to-uc

This message indicates that the linter has found a table that has been migrated to Unity Catalog. The user must ensure that the table is available in Unity Catalog.

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to-json-in-shared-clusters

toJson() is not available on Unity Catalog clusters in Shared access mode. Use toSafeJson() on DBR 13.3 LTS or above to get a subset of command context information. Example code that triggers this message:

dbutils.notebook.entry_point.getDbutils().notebook().getContext().toSafeJson()

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unsupported-magic-line

This message indicates the code that could not be analysed by UCX. User must check the code manually.

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Utility commands

logs command

$ databricks labs ucx logs [--workflow WORKFLOW_NAME] [--debug]

This command displays the logs of the last run of the specified workflow. If no workflow is specified, it displays the logs of the workflow that was run the last. This command is useful for developers and administrators who want to check the logs of the last run of a workflow and ensure that it was executed as expected. It can also be used for debugging purposes when a workflow is not behaving as expected. By default, only INFO, WARNING, and ERROR logs are displayed. To display DEBUG logs, use the --debug flag.

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ensure-assessment-run command

databricks labs ucx ensure-assessment-run

This command ensures that the assessment workflow was run on a workspace. This command will block until job finishes. Failed workflows can be fixed with the repair-run command. Workflows and their status can be listed with the workflows command.

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update-migration-progress command

databricks labs ucx update-migration-progress

This command runs the (experimental) migration progress workflow to update the migration status of workspace resources that need to be migrated. It does this by triggering the migration-progress-experimental workflow to run on a workspace and waiting for it to complete.

Workflows and their status can be listed with the workflows command, while failed workflows can be fixed with the repair-run command.

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repair-run command

databricks labs ucx repair-run --step WORKFLOW_NAME

This command repairs a failed UCX Workflow. This command is useful for developers and administrators who want to repair a failed job. It can also be used to debug issues related to job failures. This operation can also be done via user interface. Workflows and their status can be listed with the workflows command.

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workflows command

See the migration process diagram to understand the role of each workflow in the migration process.

$ databricks labs ucx workflows
Step                                  State    Started
assessment                            RUNNING  1 hour 2 minutes ago
099-destroy-schema                    UNKNOWN  <never run>
migrate-groups                        UNKNOWN  <never run>
remove-workspace-local-backup-groups  UNKNOWN  <never run>
validate-groups-permissions           UNKNOWN  <never run>

This command displays the deployed workflows and their state in the current workspace. It fetches the latest job status from the workspace and prints it in a table format. This command is useful for developers and administrators who want to check the status of UCX workflows and ensure that they have been executed as expected. It can also be used for debugging purposes when a workflow is not behaving as expected. Failed workflows can be fixed with the repair-run command.

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open-remote-config command

databricks labs ucx open-remote-config

This command opens the remote configuration file in the default web browser. It generates a link to the configuration file and opens it using the webbrowser.open() method. This command is useful for developers and administrators who want to view or edit the remote configuration file without having to manually navigate to it in the workspace. It can also be used to quickly access the configuration file from the command line. Here's the description of configuration properties:

  • inventory_database: A string representing the name of the inventory database.
  • workspace_group_regex: An optional string representing the regular expression to match workspace group names.
  • workspace_group_replace: An optional string to replace the matched group names with.
  • account_group_regex: An optional string representing the regular expression to match account group names.
  • group_match_by_external_id: A boolean value indicating whether to match groups by their external IDs.
  • include_group_names: An optional list of strings representing the names of groups to include for migration.
  • renamed_group_prefix: An optional string representing the prefix to add to renamed group names.
  • instance_pool_id: An optional string representing the ID of the instance pool.
  • warehouse_id: An optional string representing the ID of the warehouse.
  • connect: An optional Config object representing the configuration for connecting to the warehouse.
  • num_threads: An optional integer representing the number of threads to use for migration.
  • database_to_catalog_mapping: An optional dictionary mapping source database names to target catalog names.
  • default_catalog: An optional string representing the default catalog name.
  • skip_tacl_migration: Optional flag, allow skipping TACL migration when migrating tables or creating catalogs and schemas.
  • default_owner_group: Assigns this group to all migrated objects (catalogs, databases, tables, views, etc.). The group has to be an account group and the user running the migration has to be a member of this group.
  • log_level: An optional string representing the log level.
  • workspace_start_path: A string representing the starting path for notebooks and directories crawler in the workspace.
  • instance_profile: An optional string representing the name of the instance profile.
  • spark_conf: An optional dictionary of Spark configuration properties.
  • override_clusters: An optional dictionary mapping job cluster names to existing cluster IDs.
  • policy_id: An optional string representing the ID of the cluster policy.
  • include_databases: An optional list of strings representing the names of databases to include for migration.

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installations command

$ databricks labs ucx installations
...
13:49:16  INFO [d.labs.ucx] Fetching installations...
13:49:17  INFO [d.l.blueprint.parallel][finding_ucx_installations_5] finding ucx installations 10/88, rps: 22.838/sec
13:49:17  INFO [d.l.blueprint.parallel][finding_ucx_installations_9] finding ucx installations 20/88, rps: 35.002/sec
13:49:17  INFO [d.l.blueprint.parallel][finding_ucx_installations_2] finding ucx installations 30/88, rps: 51.556/sec
13:49:18  INFO [d.l.blueprint.parallel][finding_ucx_installations_9] finding ucx installations 40/88, rps: 56.272/sec
13:49:18  INFO [d.l.blueprint.parallel][finding_ucx_installations_19] finding ucx installations 50/88, rps: 67.382/sec
...
Path                                      Database  Warehouse
/Users/serge.smertin@databricks.com/.ucx  ucx       675eaf1ff976aa98

This command displays the installations by different users on the same workspace. It fetches all the installations where the ucx package is installed and prints their details in JSON format. This command is useful for administrators who want to see which users have installed ucx and where. It can also be used to debug issues related to multiple installations of ucx on the same workspace.

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report-account-compatibility command

databricks labs ucx report-account-compatibility --profile labs-azure-account
12:56:09  INFO [databricks.sdk] Using Azure CLI authentication with AAD tokens
12:56:09  INFO [d.l.u.account.aggregate] Generating readiness report
12:56:10  INFO [databricks.sdk] Using Azure CLI authentication with AAD tokens
12:56:10  INFO [databricks.sdk] Using Azure CLI authentication with AAD tokens
12:56:15  INFO [databricks.sdk] Using Azure CLI authentication with AAD tokens
12:56:15  INFO [d.l.u.account.aggregate] Querying Schema ucx
12:56:21  WARN [d.l.u.account.aggregate] Workspace 4045495039142306 does not have UCX installed
12:56:21  INFO [d.l.u.account.aggregate] UC compatibility: 30.303030303030297% (69/99)
12:56:21  INFO [d.l.u.account.aggregate] cluster type not supported : LEGACY_TABLE_ACL: 22 objects
12:56:21  INFO [d.l.u.account.aggregate] cluster type not supported : LEGACY_SINGLE_USER: 24 objects
12:56:21  INFO [d.l.u.account.aggregate] unsupported config: spark.hadoop.javax.jdo.option.ConnectionURL: 10 objects
12:56:21  INFO [d.l.u.account.aggregate] Uses azure service principal credentials config in cluster.: 1 objects
12:56:21  INFO [d.l.u.account.aggregate] No isolation shared clusters not supported in UC: 1 objects
12:56:21  INFO [d.l.u.account.aggregate] Data is in DBFS Root: 23 objects
12:56:21  INFO [d.l.u.account.aggregate] Non-DELTA format: UNKNOWN: 5 objects

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export-assessment command

databricks labs ucx export-assessment

The export-assessment command is used to export UCX assessment results to a specified location. When you run this command, you will be prompted to provide details on the destination path and the type of report you wish to generate. If you do not specify these details, the command will default to exporting the main results to the current directory. The exported file will be named based on the selection made in the format. Eg: export_{query_choice}_results.zip

  • Choose a path to save the UCX Assessment results:

    • Description: Specify the path where the results should be saved. If not provided, results will be saved in the current directory.

  • Choose which assessment results to export:

    • Description: Select the type of results to export. Options include:
      • azure
      • estimates
      • interactive
      • main
    • Default: main

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Metastore related commands

These commands are used to assign a Unity Catalog metastore to a workspace. The metastore assignment is a pre-requisite for any further migration steps.

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show-all-metastores command

databricks labs ucx show-all-metastores [--workspace-id <workspace-id>]

This command lists all the metastores available to be assigned to a workspace. If no workspace is specified, it lists all the metastores available in the account. This command is useful when there are multiple metastores available within a region, and you want to see which ones are available for assignment.

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assign-metastore command

databricks labs ucx assign-metastore --workspace-id <workspace-id> [--metastore-id <metastore-id>]

This command assigns a metastore to a workspace with --workspace-id. If there is only a single metastore in the workspace region, the command automatically assigns that metastore to the workspace. If there are multiple metastores available, the command prompts for specification of the metastore (id) you want to assign to the workspace.

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create-ucx-catalog command

databricks labs ucx create-ucx-catalog
16:12:59  INFO [d.l.u.hive_metastore.catalog_schema] Validating UC catalog: ucx
Please provide storage location url for catalog: ucx (default: metastore): ...
16:13:01  INFO [d.l.u.hive_metastore.catalog_schema] Creating UC catalog: ucx

Create and setup UCX artifact catalog. Amongst other things, the artifacts are used for tracking the migration progress across workspaces.

Table migration commands

These commands are vital part of table migration process process and require the assessment workflow and group migration workflow to be completed. See the migration process diagram to understand the role of the table migration commands in the migration process.

The first step is to run the principal-prefix-access command to identify all the storage accounts used by tables in the workspace and their permissions on each storage account.

If you don't have any storage credentials and external locations configured, you'll need to run the migrate-credentials command to migrate the service principals and migrate-locations command to create the external locations. If some of the external locations already exist, you should run the validate-external-locations command. You'll need to create the uber principal with the access to all storage used to tables in the workspace, so that you can migrate all the tables. If you already have the principal, you can skip this step.

Ask your Databricks Account admin to run the sync-workspace-info command to sync the workspace information with the UCX installations. Once the workspace information is synced, you can run the create-table-mapping command to align your tables with the Unity Catalog, create catalogs and schemas and start the migration using migrate-tables command. During multiple runs of the table migration workflow, you can use the revert-migrated-tables command to revert the tables that were migrated in the previous run. You can also skip the tables that you don't want to migrate using the skip command.

Once you're done with the table migration, proceed to the code migration.

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principal-prefix-access command

databricks labs ucx principal-prefix-access [--subscription-ids <Azure Subscription ID>] [--aws-profile <AWS CLI profile>]

This command depends on results from the assessment workflow and requires AWS CLI or Azure CLI to be installed and authenticated for the given machine. This command identifies all the storage accounts used by tables in the workspace and their permissions on each storage account. Once you're done running this command, proceed to the migrate-credentials command.

The "prefix" refers to the start - i.e. prefix - of table locations that point to the cloud storage location.

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Access for AWS S3 Buckets

databricks labs ucx principal-prefix-access --aws-profile test-profile

Use to identify all instance profiles in the workspace, and map their access to S3 buckets. Also captures the IAM roles which has UC arn listed, and map their access to S3 buckets This requires aws CLI to be installed and configured.

For AWS this command produces a file named aws_instance_profile_info.csv. It has the following format:

role_arn resource_type privilege resource_path
arn:aws:iam::1234:instance-profile/instance-profile1 s3 WRITE_FILES s3://s3_bucket1/path1

Once done, proceed to the migrate-credentials command.

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Access for Azure Storage Accounts

databricks labs ucx principal-prefix-access --subscription-ids test-subscription-id

Use to identify all storage account used by tables, identify the relevant Azure service principals and their permissions on each storage account. The command is used to identify Azure Service Principals, which have Storage Blob Data Contributor, Storage Blob Data Reader, Storage Blob Data Owner roles, or custom read/write roles on ADLS Gen2 locations that are being used in Databricks. This requires Azure CLI to be installed and configured via az login. It outputs azure_storage_account_info.csv which will be later used by migrate-credentials command to create UC storage credentials. Note: This cmd only lists azure storage account gen2, storage format wasb:// or adl:// are not supported in UC and those storage info will be skipped.

Once done, proceed to the migrate-credentials command.

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create-missing-principals command (AWS Only)

databricks labs ucx create-missing-principals --aws-profile <aws_profile> --single-role <single_role>

This command identifies all the S3 locations that are missing a UC compatible role and creates them. It takes single-role optional parameter. If set to True, it will create a single role for all the S3 locations. Otherwise, it will create a role for each S3 location.

Two optional parameter are available for this command: --role-name - This parameter is used to set the prefix for the role name. The default value is UCX-ROLE. --role-policy - This parameter is used to set the prefix for the role policy name. The default value is UCX-POLICY.

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delete-missing-principals command (AWS Only)

databricks labs ucx delete-missing-principals --aws-profile <aws_profile>

This command helps to delete the IAM role created by UCX. It lists all the IAM Roles generated by the principal-prefix-access command and allows user to select multiple roles to delete. It also checks if selected roles are mapped to any storage credentials and asks for confirmation from user. Once confirmed, it deletes the role and its associated inline policy.

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create-uber-principal command

databricks labs ucx create-uber-principal [--subscription-ids X]

Requires Cloud IAM admin privileges.

Once the assessment workflow complete, you should run this command to create a service principal with the read-only access to all storage used by tables in this workspace. It will also configure the UCX Cluster Policy & SQL Warehouse data access configuration to use this service principal for migration workflows. Once migration is complete, this service principal should be unprovisioned.

On Azure, it creates a principal with Storage Blob Data Contributor role assignment on every storage account using Azure Resource Manager APIs.

This command is one of prerequisites for the table migration process.

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migrate-credentials command

databricks labs ucx migrate-credentials

For Azure, this command prompts to confirm performing the following credential migration steps:

  1. [RECOMMENDED] For each storage account, create access connectors with managed identities that have the Storage Blob Data Contributor role on the respective storage account. A storage credential is created for each access connector.
  2. Migrate Azure Service Principals, which have Storage Blob Data Contributor, Storage Blob Data Reader, Storage Blob Data Owner, or custom roles on ADLS Gen2 locations that are being used in Databricks, to UC storage credentials. The Azure Service Principals to location mapping are listed in /Users/{user_name}/.ucx/azure_storage_account_info.csv which is generated by principal-prefix-access command. Please review the file and delete the Service Principals you do not want to be migrated. The command will only migrate the Service Principals that have client secret stored in Databricks Secret.

Warning: Service principals used to access storage accounts behind firewalls might cause connectivity issues. We recommend to use access connectors instead.

For AWS, this command migrates AWS Instance Profiles that are being used in Databricks, to UC storage credentials. The AWS Instance Profiles to location mapping are listed in {workspace ucx folder}/aws_instance_profile_info.csv which is generated by principal_prefix_access command. Please review the file and delete the Instance Profiles you do not want to be migrated.
The aws_profile parameter indicates the aws profile to use.

Once you're done with this command, run validate-external-locations command after this one.

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validate-external-locations command

databricks labs ucx validate-external-locations

Once the assessment workflow finished successfully, storage credentials are configured, run this command to validate and report the missing Unity Catalog external locations to be created.

This command validates and provides mapping to external tables to external locations, also as Terraform configurations.

Once you're done with this command, proceed to the migrate-locations command.

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migrate-locations command

databricks labs ucx migrate-locations

Once the assessment workflow finished successfully, and storage credentials are configured, run this command to have Unity Catalog external locations created. The candidate locations to be created are extracted from guess_external_locations task in the assessment job. You can run validate-external-locations command to check the candidate locations.

Location ACLs: migrate-locations command applies any location ACL from existing cluster. For Azure, it checks if there are any interactive cluster or SQL warehouse which has service principals configured to access storage. It maps the storage account to the external location created and grants CREATE_EXTERNAL_TABLE, CREATE_EXTERNAL_VOLUME and READ_FILES permission on the location to all the user who have access to the interactive cluster or SQL warehouse For AWS, it checks any instance profiles mapped to the interactive cluster or SQL warehouse. It checks the mapping of instance profiles to the bucket. It then maps the bucket to the external locations created and grants CREATE_EXTERNAL_TABLE, CREATE_EXTERNAL_VOLUME and READ_FILES permission on the location to all the user who have access to the interactive cluster or SQL warehouse

Once you're done with this command, proceed to the create-table-mapping command.

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create-table-mapping command

databricks labs ucx create-table-mapping

Once the assessment workflow finished successfully workspace info is synchronized, run this command to create the initial table mapping for review in CSV format in the Databricks Workspace:

workspace_name,catalog_name,src_schema,dst_schema,src_table,dst_table
labs-azure,labs_azure,default,default,ucx_tybzs,ucx_tybzs

The format of the mapping file is as follows:

columns: workspace_name catalog_name src_schema dst_schema src_table dst_table
values: data_engineering_ws de_catalog database1 database1 table1 table1

You are supposed to review this mapping and adjust it if necessary. This file is in CSV format, so that you can edit it easier in your favorite spreadsheet application.

Once you're done with this command, create catalogs and schemas. During multiple runs of the table migration workflow, you can use the revert-migrated-tables command to revert the tables that were migrated in the previous run. You can also skip the tables that you don't want to migrate using the skip command.

This command is one of prerequisites for the table migration process.

Once you're done with table migration, proceed to the code migration.

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skip command

databricks labs ucx skip --schema X [--table Y] [--view Z]

Anytime after create-table-mapping command is executed, you can run this command.

This command allows users to skip certain schemas, tables or views during the table migration process. The command takes --schema and, optionally, --table and --view flags to specify the schema, table or view to skip. If no --table flag is provided, all tables in the specified HMS database are skipped. The --table and --view can only be used exclusively. This command is useful to temporarily disable migration of a particular schema, table or view.

Once you're done with table migration, proceed to the code migration.

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unskip command

databricks labs ucx unskip --schema X [--table Y] [--view Z]

This command removes the mark set by the skip command on the given schema, table or view.

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create-catalogs-schemas command

databricks labs ucx create-catalogs-schemas

After create-table-mapping command is executed, you can run this command to have the required UC catalogs and schemas created. This command is supposed to be run before migrating tables to UC using table migration process. Catalog & Schema ACL: create-catalogs-schemas command also applies any catalog and schema ACL from existing clusters. For Azure it checks if there are any interactive cluster or sql warehouse which has service principals configured to access storage. It maps the storage account to the tables which has external location on those storage account created and grants USAGE access to the schema and catalog if at least one such table is migrated to it. For AWS, it checks any instance profiles mapped to the interactive cluster or sql warehouse. It checks the mapping of instance profiles to the bucket. It then maps the bucket to the tables which has external location on those bucket created and grants USAGE access to the schema and catalog if at least one such table is migrated to it. [back to top]

assign-owner-group command

databricks labs ucx assign-owner-group

This command assigns the owner group to the UCX catalog and all migrated tables. The owner group is an account group that will be designated as an owner to all migrated objects (catalogs, schemas, tables, views). The principal running the command and later, the migration workflows, is required to be a member of this group. The command will list all the groups the principal is a member of and allow the selection of the owner group. It sets the default_owner_group property in the config.yml file.

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migrate-tables command

databricks labs ucx migrate-tables

Anytime after create-table-mapping command is executed, you can run this command.

This command kicks off the table migration process. It triggers the migrate-tables workflow, and if there are HiveSerDe tables detected, prompt whether to trigger the migrate-external-hiveserde-tables-in-place-experimental workflow.

Table and View ACL: migrate-tables command also applies any table and view ACL from existing clusters. For Azure it checks if there are any interactive cluster or sql warehouse which has service principals configured to access storage. It maps the storage account to the tables which has external location on those storage account created and grants either SELECT permission if the service principal only has read access on the storage account and ALL_PRIVILEGES if the service principal has write access on the storage account For AWS, it checks any instance profiles mapped to the interactive cluster or sql warehouse. It checks the mapping of instance profiles to the bucket. It then maps the bucket to the tables which has external location on those bucket created and grants either SELECT permission if the instance profile only has read access on the bucket and ALL_PRIVILEGES if the instance profile has write access on the bucket.

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revert-migrated-tables command

databricks labs ucx revert-migrated-tables --schema X --table Y [--delete-managed]

Anytime after create-table-mapping command is executed, you can run this command.

This command removes the upgraded_from property on a migrated table for re-migration in the table migration process. This command is useful for developers and administrators who want to revert the migration of a table. It can also be used to debug issues related to table migration.

Go back to the create-table-mapping command after you're done with this command.

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move command

databricks labs ucx move --from-catalog A --from-schema B --from-table C --to-catalog D --to-schema E

This command moves a UC table/tables from one schema to another schema after the table migration process. This is useful for developers and administrators who want to adjust their catalog structure after tables upgrade.

Users will be prompted whether tables/view are dropped after moving to new schema. This only applies to MANAGED tables and views.

This command moves different table types differently:

  • MANAGED tables are deep-cloned to the new schema.
  • EXTERNAL tables are dropped from the original schema, then created in the target schema using the same location. This is due to Unity Catalog not supporting multiple tables with overlapping paths
  • VIEW are recreated using the same view definition.

This command supports moving multiple tables at once, by specifying * as the table name.

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alias command

databricks labs ucx alias --from-catalog A --from-schema B --from-table C --to-catalog D --to-schema E

This command aliases a UC table/tables from one schema to another schema in the same or different catalog. It takes a WorkspaceClient object and from and to parameters as parameters and aliases the tables using the TableMove class. This command is useful for developers and administrators who want to create an alias for a table. It can also be used to debug issues related to table aliasing.

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Code migration commands

See the migration process diagram to understand the role of the code migration commands in the migration process.

After you're done with the table migration, you can proceed to the code migration.

Once you're done with the code migration, you can run the cluster-remap command to remap the clusters to be UC compatible.

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lint-local-code command

databricks labs ucx lint-local-code

At any time, you can run this command to assess all migrations required in a local directory or a file. It only takes seconds to run and it gives you an initial overview of what needs to be migrated without actually performing any migration. A great way to start a migration!

This command detects all dependencies, and analyzes them. It is still experimental and at the moment only supports Python and SQL files. We expect this command to run within a minute on code bases up to 50.000 lines of code. Future versions of ucx will add support for more source types, and more migration details.

When run from an IDE terminal, this command generates output as follows: img.png With modern IDEs, clicking on the file link opens the file at the problematic line

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migrate-local-code command

databricks labs ucx migrate-local-code

(Experimental) Once table migration is complete, you can run this command to migrate all python and SQL files in the current working directory. This command is highly experimental and at the moment only supports Python and SQL files and discards code comments and formatting during the automated transformation process.

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migrate-dbsql-dashboards command

databricks labs ucx migrate-dbsql-dashboards [--dashboard-id <dashboard-id>]

(Experimental) Once table migration is complete, you can run this command to migrate all Databricks SQL dashboards in the workspace. At this moment, this command is highly experimental and discards formatting during the automated transformation process.

This command tags dashboards & queries that have been migrated with migrated by UCX tag. The original queries are also backed up in the ucx installation folder, to allow for easy rollback (see revert-dbsql-dashboards command).

This command can be run with --dashboard-id flag to migrate a specific dashboard.

This command is incremental and can be run multiple times to migrate new dashboards.

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revert-dbsql-dashboards command

databricks labs ucx revert-dbsql-dashboards [--dashboard-id <dashboard-id>]

(Experimental) This command reverts the migration of Databricks SQL dashboards in the workspace, after migrate-dbsql-dashboards command is executed.

This command can be run with --dashboard-id flag to migrate a specific dashboard.

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Cross-workspace installations

When installing UCX across multiple workspaces, administrators need to keep UCX configurations in sync. UCX will prompt you to select an account profile that has been defined in ~/.databrickscfg. If you don't have one, authenticate your machine with:

  • databricks auth login --host https://accounts.cloud.databricks.com/ (AWS)
  • databricks auth login --host https://accounts.azuredatabricks.net/ (Azure)

Ask your Databricks Account admin to run the sync-workspace-info command to sync the workspace information with the UCX installations. Once the workspace information is synced, you can run the create-table-mapping command to align your tables with the Unity Catalog.

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sync-workspace-info command

databricks --profile ACCOUNTS labs ucx sync-workspace-info
14:07:07  INFO [databricks.sdk] Using Azure CLI authentication with AAD tokens
14:07:07  INFO [d.labs.ucx] Account ID: ...
14:07:10  INFO [d.l.blueprint.parallel][finding_ucx_installations_16] finding ucx installations 10/88, rps: 16.415/sec
14:07:10  INFO [d.l.blueprint.parallel][finding_ucx_installations_0] finding ucx installations 20/88, rps: 32.110/sec
14:07:11  INFO [d.l.blueprint.parallel][finding_ucx_installations_18] finding ucx installations 30/88, rps: 39.786/sec
...

Requires Databricks Account Administrator privileges. Use --profile to select the Databricks cli profile configured with access to the Databricks account console (with endpoint "https://accounts.cloud.databricks.com/" or "https://accounts.azuredatabricks.net").

This command uploads the workspace config to all workspaces in the account where ucx is installed. This command is necessary to create an immutable default catalog mapping for table migration process and is the prerequisite for create-table-mapping command.

If you cannot get account administrator privileges in reasonable time, you can take the risk and run manual-workspace-info command to enter Databricks Workspace IDs and Databricks Workspace names.

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manual-workspace-info command

$ databricks labs ucx manual-workspace-info
14:20:36  WARN [d.l.ucx.account] You are strongly recommended to run "databricks labs ucx sync-workspace-info" by account admin,
 ... otherwise there is a significant risk of inconsistencies between different workspaces. This command will overwrite all UCX
 ... installations on this given workspace. Result may be consistent only within https://adb-987654321.10.azuredatabricks.net
Workspace name for 987654321 (default: workspace-987654321): labs-workspace
Next workspace id (default: stop): 12345
Workspace name for 12345 (default: workspace-12345): other-workspace
Next workspace id (default: stop):
14:21:19  INFO [d.l.blueprint.parallel][finding_ucx_installations_11] finding ucx installations 10/89, rps: 24.577/sec
14:21:19  INFO [d.l.blueprint.parallel][finding_ucx_installations_15] finding ucx installations 20/89, rps: 48.305/sec
...
14:21:20  INFO [d.l.ucx.account] Synchronised workspace id mapping for installations on current workspace

This command is only supposed to be run if the sync-workspace-info command cannot be run. It prompts the user to enter the required information manually and creates the workspace info. This command is useful for workspace administrators who are unable to use the sync-workspace-info command, because they are not Databricks Account Administrators. It can also be used to manually create the workspace info in a new workspace.

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create-account-groups command

$ databricks labs ucx create-account-groups [--workspace-ids 123,456,789]

Requires Databricks Account Administrator privileges. This command creates account-level groups if a workspace local group is not present in the account. It crawls all workspaces configured in --workspace-ids flag, then creates account level groups if a WS local group is not present in the account. If --workspace-ids flag is not specified, UCX will create account groups for all workspaces configured in the account.

The following scenarios are supported, if a group X:

  • Exist in workspaces A,B,C, and it has same members in there, it will be created in the account
  • Exist in workspaces A,B but not in C, it will be created in the account
  • Exist in workspaces A,B,C. It has same members in A,B, but not in C. Then, X and C_X will be created in the account

This command is useful for the setups, that don't have SCIM provisioning in place.

Once you're done with this command, proceed to the group migration workflow.

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validate-groups-membership command

$ databricks labs ucx validate-groups-membership
...
14:30:36  INFO [d.l.u.workspace_access.groups] Found 483 account groups
14:30:36  INFO [d.l.u.workspace_access.groups] No group listing provided, all matching groups will be migrated
14:30:36  INFO [d.l.u.workspace_access.groups] There are no groups with different membership between account and workspace
Workspace Group Name  Members Count  Account Group Name  Members Count  Difference

This command validates the groups to see if the groups at the account level and workspace level have different membership. This command is useful for administrators who want to ensure that the groups have the correct membership. It can also be used to debug issues related to group membership. See group migration and group migration for more details.

Valid group membership is important to ensure users has correct access after legacy table ACL is migrated in table migration process

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validate-table-locations command

$ databricks labs ucx validate-table-locations [--workspace-ids 123,456,789]
...
11:39:36  WARN [d.l.u.account.aggregate] Workspace 99999999 does not have UCX installed
11:39:37  WARN [d.l.u.account.aggregate] Overlapping table locations: 123456789:hive_metastore.database.table and 987654321:hive_metastore.database.table
11:39:37  WARN [d.l.u.account.aggregate] Overlapping table locations: 123456789:hive_metastore.database.table and 123456789:hive_metastore.another_database.table

This command validates the table locations by checking for overlapping table locations in the workspace and across workspaces. Unity catalog does not allow overlapping table locations, also not between tables in different catalogs. Overlapping table locations need to be resolved by the user before running the table migration.

Options to resolve tables with overlapping locations are:

  • Move one table and skip the other(s).
  • Duplicate the tables by copying the data into a managed table and skip the original tables.

Considerations when resolving tables with overlapping locations are:

  • Migrate the tables one workspace at a time:
    • Let later migrated workspaces read tables from the earlier migrated workspace catalogs.
    • Move tables between schemas and catalogs when it fits the data management model.
  • The tables might have different:
    • Metadata, like:
      • Column schema (names, types, order)
      • Description
      • Tags
    • ACLs

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cluster-remap command

$ databricks labs ucx cluster-remap
21:29:38  INFO [d.labs.ucx] Remapping the Clusters to UC
Cluster Name                                            Cluster Id
Field Eng Shared UC LTS Cluster                         0601-182128-dcbte59m
Shared Autoscaling Americas cluster                     0329-145545-rugby794

Please provide the cluster id's as comma separated value from the above list (default: <ALL>):

Once you're done with the code migration, you can run this command to remap the clusters to UC enabled.

This command will remap the cluster to uc enabled one. When we run this command it will list all the clusters and its id's and asks to provide the cluster id's as comma separated value which has to be remapped, by default it will take all cluster ids. Once we provide the cluster id's it will update these clusters to UC enabled.Back up of the existing cluster config will be stored in backup folder inside the installed location(backup/clusters/cluster_id.json) as a json file.This will help to revert the cluster remapping.

You can revert the cluster remapping using the revert-cluster-remap command.

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revert-cluster-remap command

$ databricks labs ucx revert-cluster-remap
21:31:29  INFO [d.labs.ucx] Reverting the Remapping of the Clusters from UC
21:31:33  INFO [d.labs.ucx] 0301-055912-4ske39iq
21:31:33  INFO [d.labs.ucx] 0306-121015-v1llqff6
Please provide the cluster id's as comma separated value from the above list (default: <ALL>):

If a customer want's to revert the cluster remap done using the cluster-remap command they can use this command to revert its configuration from UC to original one.It will iterate through the list of clusters from the backup folder and reverts the cluster configurations to original one.This will also ask the user to provide the list of clusters that has to be reverted as a prompt. By default, it will revert all the clusters present in the backup folder

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upload command

$ databricks labs ucx upload --file <file_path> --run-as-collection True
21:31:29 WARNING [d.labs.ucx] The schema of CSV files is NOT validated, ensure it is correct
21:31:29 INFO [d.labs.ucx] Finished uploading: <file_path>

Upload a file to a single workspace (--run-as-collection False) or a collection of workspaces (--run-as-collection True). This command is especially useful when uploading the same file to multiple workspaces.

download command

$ databricks labs ucx download --file <file_path> --run-as-collection True
21:31:29 INFO [d.labs.ucx] Finished downloading: <file_path>

Download a csv file from a single workspace (--run-as-collection False) or a collection of workspaces (--run-as-collection True). This command is especially useful when downloading the same file from multiple workspaces.

join-collection command

$ databricks labs ucx join-collection --workspace-ids <comma seperate list of workspace ids> --profile <account-profile>

join-collection command joins 2 or more workspaces into a collection. This helps in running supported cli commands as a collection join-collection command updates config.yml file on each workspace ucx installation with installed_workspace_ids attribute. In order to run join-collectioon command a user should:

  • be an Account admin on the Databricks account
  • be a Workspace admin on all the workspaces to be joined as a collection) or a collection of workspaces
  • have installed UCX on the workspace The join-collection command will fail and throw an error msg if the above conditions are not met.

collection eligible command

Once join-collection command is run, it allows user to run multiple cli commands as a collection. The following cli commands are eligible to be run as a collection. User can run the below commands as collection by passing an additional flag --run-as-collection=True

  • ensure-assessment-run
  • create-table-mapping
  • principal-prefix-access
  • migrate-credentials
  • create-uber-principal
  • create-missing-principals
  • validate-external-location
  • migrate-locations
  • create-catalog-schemas
  • migrate-tables
  • migrate-acls
  • migrate-dbsql-dashboards
  • validate-group-membership Ex: databricks labs ucx ensure-assessment-run --run-as-collection=True

Common Challenges and the Solutions

Users might encounter some challenges while installing and executing UCX. Please find the listing of some common challenges and the solutions below.

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Network Connectivity Issues

From local machine to the Databricks Account and Workspace: UCX installation process has to be run from the local laptop using Databricks CLI and it will deploy the latest version of UCX into the Databricks workspace. For this reason, the Databricks account and workspace needs to be accessible from the laptop. Sometimes, the workspace might have a network isolation, like it can only be reached from a VPC, or from a specific IP range.

Solution: Please check that your laptop has network connectivity to the Databricks account and workspace. If not, you might need to be connected to a VPN or configure an HTTP proxy to access your workspace.

From local machine to GitHub: UCX needs internet access to connect to GitHub (https://api.github.com and https://raw.githubusercontent.com) for downloading the tool from the machine running the installation. The installation will fail if there is no internet connectivity to these URLs.

Solution: Ensure that GitHub is reachable from the local machine. If not, make necessary changes to the network/firewall settings.

From Databricks workspace to PyPi: There are some dependent libraries which need to be installed from pypi.org to run the UCX workflows from the Databricks workspace. If the workspace doesn’t have network connectivity, then the job might fail with NO_MATCHING_DISTRIBUTION_ERROR.

Solution: Version 0.24.0 of UCX supports workspace with no internet access. Please upgrade UCX and rerun the installation. Reply yes to the question "Does the given workspace block Internet access?" asked during installation. It will then upload all necessary dependencies to the workspace. Also, please note that UCX uses both UC and non-UC enabled clusters. If you have different proxy settings for each, then please update the necessary proxies (eg. with init scripts) for each cluster type.

Local machine to Databricks Account and Workspace connection failed due to proxy and self-signed cert: When customer uses web proxy and self-singed certification, UCX may not be able to connect to Account and Workspace with following errors:

File "/Users/userabc/.databricks/labs/ucx/state/venv/lib/python3.10/site-packages/urllib3/connectionpool.py", line 466, in _make_request
    self._validate_conn(conn)
  File "/Users/userabc/.databricks/labs/ucx/state/venv/lib/python3.10/site-packages/urllib3/connectionpool.py", line 1095, in _validate_conn
    conn.connect()
  File "/Users/userabc/.databricks/labs/ucx/state/venv/lib/python3.10/site-packages/urllib3/connection.py", line 652, in connect
    sock_and_verified = _ssl_wrap_socket_and_match_hostname(
  File "/Users/userabc/.databricks/labs/ucx/state/venv/lib/python3.10/site-packages/urllib3/connection.py", line 805, in _ssl_wrap_socket_and_match_hostname
    ssl_sock = ssl_wrap_socket(
  File "/Users/userabc/.databricks/labs/ucx/state/venv/lib/python3.10/site-packages/urllib3/util/ssl_.py", line 465, in ssl_wrap_socket
    ssl_sock = _ssl_wrap_socket_impl(sock, context, tls_in_tls, server_hostname)
  File "/Users/userabc/.databricks/labs/ucx/state/venv/lib/python3.10/site-packages/urllib3/util/ssl_.py", line 509, in _ssl_wrap_socket_impl
    return ssl_context.wrap_socket(sock, server_hostname=server_hostname)
  File "/opt/homebrew/Cellar/python@3.10/3.10.14/Frameworks/Python.framework/Versions/3.10/lib/python3.10/ssl.py", line 513, in wrap_socket
    return self.sslsocket_class._create(
  File "/opt/homebrew/Cellar/python@3.10/3.10.14/Frameworks/Python.framework/Versions/3.10/lib/python3.10/ssl.py", line 1104, in _create
    self.do_handshake()
  File "/opt/homebrew/Cellar/python@3.10/3.10.14/Frameworks/Python.framework/Versions/3.10/lib/python3.10/ssl.py", line 1375, in do_handshake
    self._sslobj.do_handshake()
ssl.SSLCertVerificationError: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: self-signed certificate in certificate chain (_ssl.c:1007)

Solution: set both REQUESTS_CA_BUNDLE and CURL_CA_BUNDLE to force requests library to set verify=False as well as set SSL_CERT_DIR env var pointing to the proxy CA cert for the urllib3 library.

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Insufficient Privileges

User is not a Databricks workspace administrator: User running the installation needs to be a workspace administrator as the CLI will deploy the UCX tool into the workspace, create jobs, and dashboards.

Solution: Identify a workspace admin from your team and ask them to install UCX with their authentication, or request a workspace administrator to grant you temporary administrator privileges to run the installation. More details on the issues that you can run into if you are not an admin (and some possible solutions) can be found here.

User is not a Cloud IAM Administrator: Cloud CLI needs to be installed in the local machine for certain cloud related activities, like creating an uber principal. For this, the user needs Cloud IAM Administrator privileges.

Solution: Work with a cloud administrator in your organization to run the commands that need cloud administrator rights.

Admin privileges required for commands:

CLI command Admin privileges
install Workspace Admin
account install Account Admin
create-account-groups Account Admin
validate-groups-membership Account Admin
create-uber-principal Cloud Admin
principal-prefix-access Cloud Admin
create-missing-principals Cloud Admin
delete-missing-principals Cloud Admin
migrate-credentials Cloud Admin, Account Admin / Metastore Admin / CREATE STORAGE CREDENTIAL privilege
migrate-location Metastore Admin / CREATE EXTERNAL LOCATION privilege
create-catalogs-schemas Metastore Admin / CREATE CATALOG privilege
sync-workspace-info Account Admin
manual-workspace-info Workspace Admin

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Version Issues

Python: UCX needs Python version 3.10 or later.

Solution: Check the current version using python --version. If the version is lower than 3.10, upgrade the local Python version to 3.10 or higher.

Databricks CLI: Databricks CLI v0.213 or higher is needed.

Solution: Check the current version with databricks --version. For lower versions of CLI, update the Databricks CLI on the local machine.

UCX: When you install UCX, you get the latest version. But since UCX is being actively developed, new versions are released frequently. There might be issues if you have run the assessment with a much earlier version, and then trying to run the migration workflows with the latest UCX version.

Solution: Upgrade UCX, and rerun the assessment job before running the migration workflows. For some reason, if you want to install a specific version of UCX, you can do it using the command databricks labs install ucx@\<version\>, for example, databricks labs install ucx@v0.21.0.

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Authentication Issues

Workspace Level: If you are facing authentication issues while setting up Databricks CLI, please refer to the Cryptic errors on authentication section to resolve the common errors related to authentication, profiles, and tokens.

Account Level: Not only workspace, but account level authentication is also needed for installing UCX. If you do not have an account configured in .databrickscfg, you will get an error message ".databrickscfg does not contain account profiles; please create one first".

Solution: To authenticate with a Databricks account, consider using one of the following authentication types: OAuth machine-to-machine (M2M) authentication, OAuth user-to-machine (U2M) authentication, Basic authentication (legacy).

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Multiple Profiles in Databricks CLI

Workspace Level: More than one workspace profile can be configured in the .databrickscfg file. For example, you can have profiles set for Dev and Prod workspaces. You want to install UCX only for the Prod workspace.

Solution: The Databricks CLI provides an option to select the profile using --profile \<profile_name\> or -p \<profile_name\>. You can test that the correct workspace is getting selected by running any Databricks CLI command. For example, you can run databricks clusters list -p prod and check that the Prod clusters are being returned. Once the profile is verified, you can run UCX install for that specific profile: databricks labs install ucx -p prod.

Account Level: Multiple account level profiles are set in the .databrickscfg file.

Solution: The installation command databricks labs install ucx will provide an option to select one account profile.

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Workspace has an external Hive Metastore (HMS)

External HMS connectivity from UCX clusters: If the workspace has an external HMS, the clusters running the UCX jobs need to have specific configurations to connect to the external HMS. Otherwise, UCX assessment will not be able to assess the tables on HMS.

Solution: Use a cluster policy before installation to set the required Spark config for connecting to the external HMS, or manually edit the cluster post-installation to have the correct configurations. Detailed steps can be found here.

External HMS connectivity from UCX SQL warehouse: UCX requires a SQL warehouse to create tables, run queries, create and refresh dashboards. If you already have a Pro or Serverless warehouse connected to the external HMS, you can select the same warehouse for UCX. You will also be given an option (during installation) to create a new warehouse for UCX. If you have never used a warehouse before, the new warehouse created might not have proper configuration set to connect to the external HMS.

Solution: Set Spark configuration for connecting to external HMS in the Admin Settings of SQL warehouse. This will only be needed if the admin settings do not have the configurations already set. For example, add spark.hadoop.javax.jdo.option.ConnectionURL <connectionstring> under Data Access Configuration of SQL Warehouse Admin Settings.

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Verify the Installation

Once the UCX command databricks labs install ucx has completed successfully, the installation can be verified with the following steps:

  1. Go to the Databricks Catalog Explorer and check if a new schema for ucx is available in Hive Metastore with all empty tables.

  2. Check that the UCX jobs are visible under Workflows.

  3. Run the assessment. This will start the UCX clusters, crawl through the workspace, and display results in the UCX dashboards. In case of external HMS, verify from the results that the assessment has analyzed the external HMS tables.

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Star History

Star History Chart

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Project Support

Please note that all projects in the databrickslabs GitHub account are provided for your exploration only, and are not formally supported by Databricks with Service Level Agreements (SLAs). They are provided AS-IS, and we do not make any guarantees of any kind. Please do not submit a support ticket relating to any issues arising from the use of these projects.

Any issues discovered through the use of this project should be filed as GitHub Issues on the Repo. They will be reviewed as time permits, but there are no formal SLAs for support.

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Automated migrations to Unity Catalog

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