Mirrored database definition

2025-07-09

This article provides a breakdown of the definition structure for mirrored database items.

Definition parts

This table lists the mirrored database definition parts.

Definition part path	Type	Required	Description
`mirroring.json`	MirroredDatabase	✅	Describes the mirrored database item
`.platform`	PlatformDetails	❌	Describes the metadata of the item

Definition part of a mirrored database item is constructed as follows:

Path: The file name, for example: mirroring.json
Payload Type: InlineBase64
Payload: See Example of payload content decoded from Base64

MirroredDatabase

Describes the mirrored database item.

Name	Type	Required	Description
`source`	SourceProperties	true	Describes the source type properties.
`target`	TargetProperties	true	Describes the target type properties.
`mountedTables`	MountedTable[]	false	Lists the tables to be mirrored from the source database. (If this property is not specified, all tables will be mirrored. The new tables will also be automatically added to replication.)

SourceProperties

Describes the source database to be mirrored.

Name	Type	Required	Description
`type`	SourceType	true	The type of the source database.
`typeProperties`	SourceTypeProperties	true	Properties for the source connection, such as `connection`, `database` and etc.

SourceType

Latest values for the source type (Additional source types may be added over time.):

Name	Description
`Snowflake`	Represents a Snowflake source.
`AzureSqlDatabase`	Represents an Azure SQL Database source.
`AzureSqlMI`	Represents an Azure SQL Managed Instance source.
`AzurePostgreSql`	Represents an Azure PostgreSQL source.
`CosmosDb`	Represents a Cosmos DB source.
`SqlServer2025`	Represents a SQL Server 2025 source.
`MSSQL`	Represents a Microsoft SQL Server 2016-2022 source.
`GenericMirror`	Represents an open mirroring source.

SourceTypeProperties

Describes the source type properties.

Name	Type	Required	Description
`connection`	Guid	false	The connection identifier for the source database. Not required for `GenericMirror` source type.
`database`	String	false	The name of the source database. Not required for `GenericMirror`, `AzureSqlDatabase`, `AzureSqlMI`, or `AzurePostgreSql` source types.

TargetProperties

Describes the target type properties.

Name	Type	Required	Description
`type`	String	true	The type of the target (currently only `MountedRelationalDatabase` is supported).
`typeProperties`	TargetTypeProperties	true	Properties for the target, such as `defaultSchema` and `format`.

TargetTypeProperties

Describes the properties for the target.

Name	Type	Required	Description
`defaultSchema`	String	false	The default schema for the target.
`format`	String	true	The format for the target (currently only `Delta` is supported).

MountedTable

Describes a table to be mirrored from the source database.

Name	Type	Required	Description
`source`	MountedTableSourceProperties	true	Properties for the source table, such as `schemaName` and `tableName`.

MountedTableSourceProperties

Describes the properties for the source table.

Name	Type	Required	Description
`typeProperties`	MountedTableSourceTypeProperties	true	Type properties for the source table.

MountedTableSourceTypeProperties

Describes the type properties for the source table.

Name	Type	Required	Description
`schemaName`	String	true	The schema name of the source table.
`tableName`	String	true	The table name of the source table.

`mirroring.json` example

To see how to create a JSON file describing a mirrored database item for various sources, see mirrored database definitions for various sources.

{
    "properties": {
        "source": {
            "type": "Snowflake",
            "typeProperties": {
                "connection": "a0a0a0a0-bbbb-cccc-dddd-e1e1e1e1e1e1",
                "database": "TESTDB"
            }
        },
        "target": {
            "type": "MountedRelationalDatabase",
            "typeProperties": {
                "defaultSchema": "dbo",
                "format": "Delta"
            }
        },
        "mountedTables": [
            {
                "source": {
                    "typeProperties": {
                        "schemaName": "dbo",
                        "tableName": "testtable"
                    }
                }
            }
        ]
    }
}

Definition example

Here's an example of a Base64-encoded mirrored database definition, where the content from mirroring.json example is encoded in Base64 and placed in the payload field with the path set to mirroring.json:

{
  "displayName": "myMirroredDatabase",
  "type": "MirroredDatabase",
  "description": "Create Mirrored Database item with definition",
  "definition": {
    "parts": [
      {
        "path": "mirroring.json",
        "payload": "<base64 encoded string>",
        "payloadType": "InlineBase64"
      },
      {
        "path": ".platform",
        "payload": "<base64 encoded string>",
        "payloadType": "InlineBase64"
      }
    ]
  }
}

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