Data Warehousing: Data(base) Mirroring in Microsoft Fabric (New feature)

Data Warehousing Series

Microsoft recently announced [4] the preview of a new Fabric feature called Mirroring, a low-cost, low-latency fully managed service that allows to replicate data from various systems together into OneLake [1]. Currently only Azure SQL Database, Azure Cosmos DB, and Snowflake are supported, though probably more database vendors will be targeted soon. 

For Microsoft Fabric's data engineers, data scientists and data warehouse professionals this feature is huge as importance because they don't need to care anymore about making the data available in Microsoft Fabric, which involves a considerable amount of work. 

Usually, at least for flexibility, transparence, performance and standardization, data professionals prefer to extract the data 1:1 from the source systems into a landing zone in the data warehouse or data/delta lake from where the data are further processed as needed. One data pipeline is thus built for every table in scope, which sometimes is a 10–15-minute effort per table, when the process is standardized, though upon case the effort is much higher if troubleshooting (e.g. data type incompatibility or support) or further logic changes are involved. Maintaining such data pipelines can prove to be costly over time, especially when periodic changes are needed. 

Microsoft lists other downsides of the ETL approach - restricted access to data changes, friction between people, processes, and technology, respectively the effort needed to create the pipelines, and the time needed for importing the data [1]. There's some truth is each of these points, though everything is relative. For big tables, however, refreshing all the data overnight can prove to be time-consuming and costly, especially when the data don't lie within the same region, respectively data center. Unless the data can be refreshed incrementally, the night runs can extend into the day, will all the implications that derive from this - not having actual data, which decreases the trust in reports, etc. There are tricks to speed up the process, though there are limits to what can be done. 

With mirroring, the replication of data between data sources and the analytics platform is handled in the background, after an initial replication, the changes in the source systems being reflected with a near real-time latency into OneLake, which is amazing! This allows building near real-time reporting solutions which can help the business in many ways - reviewing (and correcting in the data source) records en masse, faster overview of what's happening in the organizations, faster basis for decision-making, etc. Moreover, the mechanism is fully managed by Microsoft, which is thus responsible for making sure that the data are correctly synchronized. Only from this perspective 10-20% from the effort of building an analytics solution is probably reduced.

Mirroring in Microsoft Fabric (adapted after [2])

According to the documentation, one can replicate a whole database or choose individual regular tables (currently views aren't supported [3]), stop, restart, or remove a table from a mirroring. Moreover, through sharing, users can grant to other users or groups of users access to a mirrored database without giving access to the workspace and the rest of its items [1]. 

The data professionals and citizens can write then cross-database queries against the mirrored databases, warehouses, and the SQL analytics endpoints of lakehouses, combining data from all these sources into a single T-SQL query, which opens lot of opportunities especially in what concerns the creation of an enterprise semantic model, which should be differentiated from the semantic model created by default by the mirroring together with the SQL analytics endpoint.

Considering that the data is replicated into delta tables, one can take advantage of all the capabilities available with such tables - data versioning, time travel, interoperability and/or performance, respectively direct consumption in Power BI.

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References:
[1] Microsoft Learn - Microsoft Fabric (2024) What is Mirroring in Fabric? (link)
[2] Microsoft Learn - Microsoft Fabric (2024) Mirroring Azure SQL Database [Preview] (link)
[3] Microsoft Learn - Microsoft Fabric (2024) Frequently asked questions for Mirroring Azure SQL Database in Microsoft Fabric [Preview] (link)
[4] Microsoft Fabric Updates Blog (2024) Announcing the Public Preview of Mirroring in Microsoft Fabric, by Charles Webb (link)

Microsoft Fabric: Mirroring (Notes)

Disclaimer: This is work in progress intended to consolidate information from various sources.
Last updated: 18-Apr-2024

Mirroring in Microsoft Fabric (adapted after [2])

Mirroring

• low-cost, low-latency fully managed service that allows to replicate data from various systems together into OneLake [1]
• supported in Azure SQL Database, Azure Cosmos DB, Snowflake [1]
• ⇒ replaces ETL pipelines
• ⇐ manages the replication of data into OneLake and conversion to Parquet [1]
• changes have a near real-time latency [3]
• uses the source database’s CDC feature [4]
• {benefit} allows users to use a highly integrated, end-to-end, and easy-to-use service [1]
• the mirrored data can be used in Power BI
• ⇐ since tables are all v-ordered delta tables [3]
• {benefit} the delta tables can then be used in every Fabric experience, allowing users to accelerate their journey into Fabric [1]
• {restriction} replication of views is currently not supported [3]
• {benefit} allows to write cross-database queries against the mirrored databases, warehouses, and the SQL analytics endpoints of Lakehouses in a single T-SQL query [1]
• landing zone in OneLake 
• stores both the snapshot and change data [3]
• ⇐ improves performance when converting files into delta verti-parquet [3]
• {operation} enable the mirroring 
• by creating a secure connection to the operational data source
• an entire database or individual tables can be replicated 
• creates three items in the targeted workspace:
• the mirrored database
• a SQL analytics endpoint
• a Default semantic model
• the same source database can be mirrored multiple times
• ⇐ though usually not needed
• scenario: replicating data to different types of environments
• {operation} stopping the mirroring
• stops the replication in the source database, but a copy of the tables is kept in OneLake [3]
• {operation} restarting the mirroring 
• results in all data being replicated from the start [3]
• {operation} remove a table from mirroring
• the table is no longer replicated and its data is deleted from OneLake [3]
• {operation} sharing
• users grant other users or groups of users access to a mirrored database without giving access to the workspace and the rest of its items [1]
• access is also granted to the SQL analytics endpoint and associated default semantic model [1]
• shared mirrored databases can be found through either
• Data Hub
• Shared with Me section in Microsoft Fabric
• triggers an initial replication
• {requirement} [licensing] requires Power BI Premium, Fabric Capacity, or Trial Capacity
• {feature} monitoring
• {benefit} allows to gain insights into mirroring operations and when the replica in Fabric OneLake was last refreshed [4]
• [Azure SQL Database] 
• {restriction} doesn't support Azure SQL Database logical servers behind an AVN or private networking [2]
• {requirement} update the Azure SQL logical server firewall rules to Allow public network access [2]
• {requirement} enable the Allow Azure services option to connect to your Azure SQL Database logical server [2]
• {restriction}
•  access through the Power BI Gateway or behind a firewall is unsupported [3]
• authentication
• SQL authentication with user name and password
• Microsoft Entra ID
• Service Principal
• {troubleshooting} check if the changes properly flow
• via sys.dm_change_feed_log_scan_sessions DMV
• {troubleshooting} check if there are any problems reported
• via sys.dm_change_feed_errors DMV
• {troubleshooting} check if the mirroring was properly enabled
• via sp_help_change_feed stored procedure 
• {troubleshooting} disable mirroring
• via sp_change_feed_disable_db stored procedure

Acronyms:
AVN - Azure Virtual Network
CDC - Change Data Capture

ETL - Extract, Transfer, Load

DMV - Dynamic Management View

References:
[1] Microsoft Learn - Microsoft Fabric (2024) What is Mirroring in Fabric? (link)
[2] Microsoft Learn - Microsoft Fabric (2024) Mirroring Azure SQL Database [Preview] (link)
[3] Microsoft Learn - Microsoft Fabric (2024) Frequently asked questions for Mirroring Azure SQL Database in Microsoft Fabric [Preview] (link)
[4] Microsoft Fabric Updates Blog (2023) (link)

Resources:
[1] Tutorial: Configure Microsoft Fabric mirrored databases from Azure SQL Database [Preview] (link)
[2] Microsoft Fabric Updates Blog (2024) Announcing the Public Preview of Mirroring in Microsoft Fabric, by Charles Webb (link)

SQL Server New Features: Copilot in Azure SQL Database is in Private Preview (SQL Reloaded)

Following the news on Copilot and its adoption in the various areas, probably you asked yourself when it will become available in SQL Server. The good news is that the Copilot in Azure SQL Database is already in Private Preview (see [1], [2]). The bad news is that for the early adoption program, Microsoft looks only for customers that can provide feedback based on real-world use cases, and one will need a valid Tenant ID for signing up for the PP.

The new feature comes with two Azure portal experiences:

• Natural language to SQL: within the Azure portal query editor the natural language prompts are translated into SQL;
• Azure Copilot integration: provides customers with self-guided assistance for managing databases and troubleshooting. 

In the Data Exposed webcast with Anna Hoffman [1], the invitee, Joe Sack, showcases the use of both experiences. In what concerns the first experience, besides simple joins, Joe also showcased the use of a PIVOT based on the prompt:

"Show me a pivot summary table that displays the total number of properties sold in each year from 2020 to 2023".

-- output from Copilot
SELECT *
FROM 
(
	SELECT YEAR(SaleDate) AS Year, COUNT(*) AS TotalPropertiesSold
	FROM [PropertySearch].[dbo].[PropertyHistory]
	WHERE YEAR(SaleDate) BETWEEN 2020 AND 2023
	GROUP BY YEAR(SalesDate)
) AS PivotDate
PIVOT
(
	SUM(TotalPropertiesSold)
	FOR Year IN ([2020], [2021], [2022], [2023]
) AS PivotTable;

Even if this is a modest example, the great thing is that it generates the skeleton on which the logic can be built, which can really help beginners, though it can be also useful for more seasoned data professionals as it saves time. Probably, in a first phase this will be the main benefit of Copilot - to generate skeletons or templates on which further logic can be built. Hopefully in time it will do much more than that.

I wonder how complex the prompts can become and how can the logic be structured to create a multistep scenario. The Copilot versions from other areas showed that complex prompts give results, the question is whether Copilot can devise the steps in an optimum manner, much like a seasoned data professional does. 

The feature utilizes for the moment the table and view names, column names, primary key, and foreign key metadata to generate T-SQL code. Probably, it makes sense to also use index and statistics information, query hints and all the arsenal usually needed by data professionals to optimize a query. Conversely, maybe the second experience could be used for optimizing and troubleshooting the query. 

I'd really love to test this feature, though probably I'll need to wait until it becomes publicly available. In the meanwhile, one can play with the GitHub Copilot [3] or install Copilot in Azure Data Studio [4].

References:
[1] Data Exposed (2024) Introducing Copilot in Azure SQL Database (Private Preview) (link)
[2] Azure SQL Blog (2024) Microsoft Copilot in Azure extends capabilities to Azure SQL Database (Private Preview) by Joe Sack (link)
[3] Azure SQL Blog (2023) GitHub Copilot for SQL Developers: Turbocharge your SQL Development, by Subhojit Basak (link)
[4] Microsoft Developer (2023) Copilot is now in Azure Data Studio and this is how it can help you! (link)

Data Warehousing: Data Warehousing and Microsoft Dynamics 365

With Dynamics 365 (D365) Online Microsoft made an important strategical move on the ERP market, however in what concerns the BI & Data Warehousing (BI/DW) area Microsoft changed the rules of the game by allowing no direct SQL access to the production environment. This primarily means that will become challenging for organizations to use the existing DW infrastructure to access the D365 data, and for Vendors and Service Providers to provide BI/DW solutions integrated within the D365 platform.

D365 includes its own data warehouse (actually data mart) designed for financial reporting however as per now it can’t be extended to support other business areas. The solution favorited by Microsoft for DW seems to be the use of an Azure SQL Database aka BYOD (Bring Your Own Database) to which entity-based data can be exported incrementally (aka incremental push) or fully (aka full push) via the Data Management Framework (DMF) packages.

Because many of the D365 tables (e.g. Inventory Transactions, Products, Customers, Vendors) were overnormalized over the years and other tables were added as part of new functionality, to hide this complexity, Microsoft introduced a new layer of abstraction formed from data entities organized within an entity store. Data entities are view-like encapsulations of the underlying D365 table schema, the data import/export from and D365 being performed extensively over these data entities via the DMF, which extends the Data Import/Export Framework (DIXF).

One can use thus a BYOD as a direct source for other reporting tools as long they support a connection to Azure, otherwise the data can be further loaded into a database into the cloud, which seems to be the best option until now, as long the organization has other data that need to be consolidated for reporting. From here on, one deals with the traditional way of reporting and the available infrastructure can be extended to use an additional data source.

The BYOD solution comes with several restrictions: a package needs to be created for each business unit, no composite data entities can be exported, data entities that don’t have a unique key can’t be exported via an incremental push, data entities can change over times (new versions being available), while during synchronization no active locks should be on the database. In addition, organizations which followed this path report also some bugs that needed to be addressed via the Microsoft support. Even if the about 1700 available data entities facilitate to some degree data consumption, they seem to be more appropriate for data migrations and data integrations than for DW workloads.

In absence of direct SQL connectivity, in theory organizations can still use SSIS or similar integration tools to connect to D365 production databases and consume data entities via the Open Data Protocol (OData), a standard that defines a set of best practices for building and consuming RESTful APIs. Besides some architectural challenges, loading big tables with transactional data is reportedly slow and impracticable for loading a data warehouse. Therefore, the usability of such an architecture becomes limited in time.

Microsoft imposed a hard limitation upon its D365 architecture by making its production database inaccessible. Of course, there’s still time for Microsoft to do some magic and pull new solutions from the technology stack hat. Unfortunately, the constraints imposed to the production environments limit organizations’ choices of building a modern and flexible data warehouse. For the future it would be great if the DMF could be used directly with standard SQL Server databases, avoiding thus the need for the intermediary Azure database, or if a real-time operational solution could be provided out-of-the-box. We’ll see what the future brings...

SQL Server Administration: End of Life for 2008 and 2008 R2 Versions

SQL Server 2008 and 2008 R2 versions are heading with steep steps toward the end of support - July 9, 2019. Besides an upgrade to upper versions, it seems there is also the opportunity to migrate to an Azure SQL Server Managed Instance, which allows a near 100% compatibility with an on-premises SQL Server installation, or to a Azure VM (see Franck Mercier’s post).

If you aren’t sure which versions of SQL Server you have in your organization here’s a script that can be run on all SQL Server 2005+ installations via SQL Server Management Studio:

SELECT SERVERPROPERTY('ComputerNamePhysicalNetBIOS') ComputerName
 , SERVERPROPERTY('Edition') Edition
 , SERVERPROPERTY('ProductVersion') ProductVersion
 , CASE Cast(SERVERPROPERTY('ProductVersion') as nvarchar(20))
     WHEN '9.00.5000.00' THEN 'SQL Server 2005'
     WHEN '10.0.6000.29' THEN 'SQL Server 2008' 
     WHEN '10.50.6000.34' THEN 'SQL Server 2008 R2' 
     WHEN '11.0.7001.0' THEN 'SQL Server 2012' 
     WHEN '12.0.6024.0' THEN 'SQL Server 2014' 
     WHEN '13.0.5026.0' THEN 'SQL Server 2016'
     WHEN '14.0.2002.14' THEN 'SQL Server 2017'
     ELSE 'unknown'
   END Product 

Resources:
[1] Microsoft (2018) How to determine the version, edition, and update level of SQL Server and its components [Online] Available from: https://support.microsoft.com/en-us/help/321185/how-to-determine-the-version-edition-and-update-level-of-sql-server-an
[2] Microsoft Blogs (2018) SQL Server 2008 end of support, by Franck Mercier [Online] Available from: https://blogs.technet.microsoft.com/franmer/2018/11/01/sql-server-2008-end-of-support-2/