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Limitations in Microsoft Fabric mirrored databases from Azure SQL Database

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Current limitations in the Microsoft Fabric mirrored databases from Azure SQL Database are listed in this page. This page is subject to change.

For troubleshooting, see:

Database level limitations

  • Fabric Mirroring for Azure SQL Database is only supported on a writable primary database.
  • Azure SQL Database cannot be mirrored if the database has: enabled Change Data Capture (CDC), Azure Synapse Link for SQL, or the database is already mirrored in another Fabric workspace.
  • The maximum number of tables that can be mirrored into Fabric is 500 tables. Any tables above the 500 limit currently cannot be replicated.
    • If you select Mirror all data when configuring Mirroring, the tables to be mirrored over are the first 500 tables when all tables are sorted alphabetically based on the schema name and then the table name. The remaining set of tables at the bottom of the alphabetical list are not mirrored over.
    • If you unselect Mirror all data and select individual tables, you are prevented from selecting more than 500 tables.

Permissions in the source database

  • Row-level security is supported, but permissions are currently not propagated to the replicated data in Fabric OneLake.
  • Object-level permissions, for example granting permissions to certain columns, are currently not propagated to the replicated data in Fabric OneLake.
  • Dynamic data masking settings are currently not propagated to the replicated data in Fabric OneLake.
  • To successfully configure Mirroring for Azure SQL Database, the principal used to connect to the source Azure SQL Database must be granted the permission ALTER ANY EXTERNAL MIRROR, which is included in higher level permission like CONTROL permission or the db_owner role.

Network and connectivity security

  • The source SQL server needs to enable Allow public network access and Allow Azure services to connect.
  • The System Assigned Managed Identity (SAMI) of the Azure SQL logical server needs to be enabled and must be the primary identity.
  • The Azure SQL Database service principal name (SPN) contributor permissions should not be removed from the Fabric mirrored database item.
  • Mirroring across Microsoft Entra tenants is not supported where an Azure SQL Database and the Fabric workspace are in separate tenants. 
  • Microsoft Purview Information Protection/sensitivity labels defined in Azure SQL Database are not cascaded and mirrored to Fabric OneLake.

Table level

  • A table that does not have a defined primary key cannot be mirrored.
    • A table using a primary key defined as nonclustered primary key cannot be mirrored.
  • A table cannot be mirrored if the primary key is one of the data types: sql_variant, timestamp/rowversion.
  • Delta lake supports only six digits of precision.
    • Columns of SQL type datetime2, with precision of 7 fractional second digits, do not have a corresponding data type with same precision in Delta files in Fabric OneLake. A precision loss happens if columns of this type are mirrored and seventh decimal second digit will be trimmed.
    • A table cannot be mirrored if the primary key is one of these data types: datetime2(7), datetimeoffset(7), time(7), where 7 is seven digits of precision.
    • The datetimeoffset(7) data type does not have a corresponding data type with same precision in Delta files in Fabric OneLake. A precision loss (loss of time zone and seventh time decimal) occurs if columns of this type are mirrored.
  • Clustered columnstore indexes are not currently supported.
  • If one or more columns in the table is of type Large Binary Object (LOB) with a size > 1 MB, the column data is truncated to size of 1 MB in Fabric OneLake.
  • Source tables that have any of the following features in use cannot be mirrored.
    • Temporal history tables and ledger history tables 
    • Always Encrypted
    • In-memory tables
    • Graph 
    • External tables 
  • The following table-level data definition language (DDL) operations aren't allowed on SQL database source tables when enabled for mirroring. 
    • Switch/Split/Merge partition
    • Alter primary key
  • When there is DDL change, a complete data snapshot is restarted for the changed table, and data is reseeded.
  • Currently, a table cannot be mirrored if it has the json or vector data type.
    • Currently, you cannot ALTER a column to the vector or json data type when a table is mirrored.

Column level

  • If the source table contains computed columns, these columns cannot be mirrored to Fabric OneLake. 
  • If the source table contains columns with one of these data types, these columns cannot be mirrored to Fabric OneLake. The following data types are unsupported for mirroring:
    • image
    • text/ntext
    • xml
    • rowversion/timestamp
    • sql_variant
    • User Defined Types (UDT)
    • geometry
    • geography
  • Column names for a SQL table cannot contain spaces nor the following characters: , ; { } ( ) \n \t =.

Warehouse limitations

  • Source schema hierarchy is not replicated to the mirrored database. Instead, source schema is flattened, and schema name is encoded into the mirrored database table name. 

Mirrored item limitations

  • User needs to be a member of the Admin/Member role for the workspace to create SQL Database mirroring. 
  • Stopping mirroring disables mirroring completely. 
  • Starting mirroring reseeds all the tables, effectively starting from scratch. 

SQL analytics endpoint limitations

Fabric regions that support Mirroring

The following are the Fabric regions that support Mirroring for Azure SQL Database:

Asia Pacific:

  • Australia East
  • Australia Southeast
  • Central India
  • East Asia
  • Japan East
  • Korea Central
  • Southeast Asia
  • South India

Europe

  • North Europe
  • West Europe
  • France Central
  • Germany West Central
  • Norway East
  • Sweden Central
  • Switzerland North
  • Switzerland West
  • UK South
  • UK West

Americas:

  • Brazil South
  • Canada Central
  • Canada East
  • Central US
  • East US
  • East US2
  • North Central US
  • West US
  • West US2

Middle East and Africa:

  • South Africa North
  • UAE North

Next step

Tutorial: Configure Microsoft Fabric mirrored databases from Azure SQL Database

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