Lakehouse Federation for Microsoft SQL Server
Preview
This feature is in Public Preview.
This article describes how to set up Lakehouse Federation to run federated queries on SQL Server data that is not managed by Databricks. To learn more about Lakehouse Federation, see Run queries using Lakehouse Federation.
To connect to a SQL Server database using Lakehouse Federation, you must create the following in your Databricks Unity Catalog metastore:
A connection to your SQL Server database.
A foreign catalog that mirrors your SQL Server database in Unity Catalog so that you can use Unity Catalog query syntax and data governance tools to manage Databricks user access to the database.
Before you begin
Workspace requirements:
Workspace enabled for Unity Catalog.
Compute requirements:
Network connectivity from your Databricks Runtime cluster or SQL warehouse to the target database systems. See Networking recommendations for Lakehouse Federation.
Databricks clusters must use Databricks Runtime 13.1 or above and the shared cluster access mode.
SQL warehouses must be Pro or Serverless.
Permissions required:
To create a connection, you must be a metastore admin or a user with the
CREATE CONNECTION
privilege on the Unity Catalog metastore attached to the workspace.To create a foreign catalog, you must have the
CREATE CATALOG
permission on the metastore and be either the owner of the connection or have theCREATE FOREIGN CATALOG
privilege on the connection.
Additional permission requirements are specified in each task-based section that follows.
Create a connection
A connection specifies a path and credentials for accessing an external database system. To create a connection, you can use Catalog Explorer or the CREATE CONNECTION
SQL command in a Databricks notebook or the Databricks SQL query editor.
Permissions required: Metastore admin or user with the CREATE CONNECTION
privilege.
In your Databricks workspace, click
Catalog.
In the left pane, expand the External Data menu and select Connections.
Click Create connection.
Enter a user-friendly Connection name.
Select a Connection type of SQL Server.
Enter the following connection properties for your SQL Server instance.
Host
Port
trustServerCertificate: Defaults to
false
. When set totrue
, the transport layer uses SSL to encrypt the channel and bypasses the certificate chain to validate trust. Leave this set to the default unless you have a specific need to bypass trust validation.User
Password
(Optional) Click Test connection to confirm that it works.
(Optional) Add a comment.
Click Create.
Run the following command in a notebook or the Databricks SQL query editor.
CREATE CONNECTION <connection-name> TYPE sqlserver
OPTIONS (
host '<hostname>',
port '<port>',
user '<user>',
password '<password>'
);
We recommend that you use Databricks secrets instead of plaintext strings for sensitive values like credentials. For example:
CREATE CONNECTION <connection-name> TYPE sqlserver
OPTIONS (
host '<hostname>',
port '<port>',
user secret ('<secret-scope>','<secret-key-user>'),
password secret ('<secret-scope>','<secret-key-password>')
)
For information about setting up secrets, see Secret management.
Create a foreign catalog
A foreign catalog mirrors a database in an external data system so that you can query and manage access to data in that database using Databricks and Unity Catalog. To create a foreign catalog, you use a connection to the data source that has already been defined.
To create a foreign catalog, you can use Catalog Explorer or the CREATE FOREIGN CATALOG
SQL command in a Databricks notebook or the Databricks SQL query editor.
Permissions required: CREATE CATALOG
permission on the metastore and either ownership of the connection or the CREATE FOREIGN CATALOG
privilege on the connection.
In your Databricks workspace, click
Catalog.
Click the Create Catalog button.
On the Create a new catalog dialog, enter a name for the catalog and select a Type of Foreign.
Select the Connection that provides access to the database that you want to mirror as a Unity Catalog catalog.
Enter the name of the Database that you want to mirror as a catalog.
Click Create.
Run the following SQL command in a notebook or Databricks SQL editor. Items in brackets are optional. Replace the placeholder values:
<catalog-name>
: Name for the catalog in Databricks.<connection-name>
: The connection object that specifies the data source, path, and access credentials.<database-name>
: Name of the database you want to mirror as a catalog in Databricks.
CREATE FOREIGN CATALOG [IF NOT EXISTS] <catalog-name> USING CONNECTION <connection-name>
OPTIONS (database '<database-name>');
Supported pushdowns
The following pushdowns are supported on all compute:
Filters
Projections
Limit
Functions: partial, only for filter expressions. (String functions, Mathematical functions, Data, Time and Timestamp functions, and other miscellaneous functions, such as Alias, Cast, SortOrder)
The following pushdowns are supported on Databricks Runtime 13.3 LTS and above, and on SQL warehouse compute version 2023.40 and above:
Aggregates
Sorting, when used with limit
The following pushdowns are not supported:
Joins
Windows functions
Data type mappings
When you read from SQL Server to Spark, data types map as follows:
SQL Server type |
Spark type |
---|---|
bigint (unsigned), decimal, money, numeric, smallmoney |
DecimalType |
smallint |
ShortType |
int, tinyint |
IntegerType |
bigint (if signed) |
LongType |
real |
FloatType |
float |
DoubleType |
char, nchar, uniqueidentifier |
CharType |
nvarchar, varchar |
VarcharType |
text, xml |
StringType |
binary, geography, geometry, image, timestamp, udt, varbinary |
BinaryType |
bit |
BooleanType |
date |
DateType |
datetime, datetime, smalldatetime, time |
TimestampType/TimestampNTZType |
*When you read from SQL Server, SQL Server datetimes
are mapped to Spark TimestampType
if preferTimestampNTZ = false
(default). SQL Server datetimes
are mapped to TimestampNTZType
if preferTimestampNTZ = true
.