When discussing SQL Server performance, we often hear our performance tool say, ‘An index is missing’, but never ‘There are too many indexes’.

However, in many databases, certain indexes are never used by business queries and they are maintained with every INSERT, UPDATE or DELETE operation.

The question is really simple:

• How much does an unused index actually cost?
• Why is an unused index a problem?

Every time there is a change to the data, SQL Server must also update all the relevant indexes, and that is not free.

As an example, I’m going to use a widely recognised database: the famous DynamicsBC.

The AUDIT

The first step in any study is always to carry out an inventory to gather all the data required for the analysis. I need the size of the database, size of each data file, size of the data and size of the indexes

I will use a query using the DMV: sys.dm_db_partition_stats

USE DynamicsBC;
GO

SELECT
DB_NAME() AS DatabaseName,
CAST(SUM(reserved_page_count) * 8.0 / 1024 AS DECIMAL(18,2)) AS TotalSizeMB,
CAST(SUM(used_page_count) * 8.0 / 1024 AS DECIMAL(18,2)) AS UsedSizeMB,
CAST((SUM(reserved_page_count) - SUM(used_page_count)) * 8.0 / 1024 AS DECIMAL(18,2)) AS FreeSizeMB,
CAST(SUM(
CASE
WHEN index_id < 2 THEN in_row_data_page_count
+ lob_used_page_count
+ row_overflow_used_page_count
ELSE 0
END
) * 8.0 / 1024 AS DECIMAL(18,2)) AS DataSizeMB,
CAST(SUM(
CASE
WHEN index_id >= 2 THEN used_page_count
ELSE 0
END
) * 8.0 / 1024 AS DECIMAL(18,2)) AS IndexSizeMB
FROM sys.dm_db_partition_stats;
GO

If we look at the ratio between the indexes and the data, we get:

64966.91/92898.87 × 100 = ~70 %

A ratio exceeding 50–60 % often requires an analysis of unused indexes, index overlap and compression.

YES, we are good with this database!

Now, let see if we have unused Indexes I use a script that I created years ago for DWH audit:

/******************************************************************************************/
--Summary
/******************************************************************************************/
USE [master];

DECLARE @sqlcmd NVARCHAR(max);
DECLARE @ExcludeFlag BIT = 0;
DECLARE @IncludeDB VARCHAR(1000);
DECLARE @ExcludeDB VARCHAR(1000);


SET  @IncludeDB = 'DynamicsBC'

SELECT @ExcludeFlag = 0;
--SELECT @ExcludeDB = 'distribution,master,model,msdb,tempdb';
 

DECLARE @InDBList TABLE (indb SYSNAME);
DECLARE @ExDBList TABLE (exdb SYSNAME);
DECLARE @dbList TABLE (dbID INT NOT NULL PRIMARY KEY, dbName SYSNAME NOT NULL);


IF (@ExcludeFlag = 0)
BEGIN
	INSERT INTO @InDBList SELECT * FROM string_split(@IncludeDB,',');
	INSERT INTO @dbList (dbID, dbName) 
		SELECT d.database_id, d.name 
		FROM sys.databases d 
		WHERE d.name IN (SELECT indb FROM @InDBList);
END
ELSE
BEGIN
--	INSERT INTO @ExDBList SELECT * FROM string_split(@ExcludeDB,',');
	INSERT INTO @dbList (dbID, dbName) 
		SELECT d.database_id, d.name 
		FROM sys.databases d 
--		WHERE d.name NOT IN (SELECT exdb FROM @ExDBList);
--		WHERE d.name NOT IN ('distribution','master','model','msdb','tempdb');

END

/*********************************************************************
Creation of the result table variable to store the information
--*********************************************************************/

IF (SELECT OBJECT_ID('tempdb.dbo.#dbUnUsedIndex')) IS NOT NULL  
	DROP TABLE dbo.#dbUnUsedIndex
CREATE TABLE #dbUnUsedIndex (
	dbID INT NOT NULL,
	dbName SYSNAME NOT NULL,
	objName SYSNAME NULL,
	idxName SYSNAME NULL,
	idxID INT NULL,
	UserSeek BIGINT NULL,
	UserScans BIGINT NULL,
	UserLookups BIGINT NULL,
	UserUpdates BIGINT NULL,
	nbRows BIGINT NULL,
	dropStatement NVARCHAR(1000) NULL)

DECLARE @dbID INT;
DECLARE @dbName SYSNAME;
DECLARE cur_dblst CURSOR 
  LOCAL STATIC READ_ONLY FORWARD_ONLY
FOR 
SELECT dbID, dbName
FROM @dbList;

OPEN cur_dblst
FETCH NEXT FROM cur_dblst INTO @dbID, @dbName
WHILE @@FETCH_STATUS = 0
BEGIN 
    --Do something with Id here

	SELECT @sqlcmd = N'
		USE [' + @dbName + ']'
		+ ' SELECT
			@dbID
			, @dbName			
			, o.name AS objName
			, i.name AS idxName
			, i.index_id AS idxID
			, dm_ius.user_seeks AS UserSeek
			, dm_ius.user_scans AS UserScans
			, dm_ius.user_lookups AS UserLookups
			, dm_ius.user_updates AS UserUpdates
			, p.TableRows AS nbRows
			, ''DROP INDEX '' + QUOTENAME(i.name)
			+ '' ON '' + QUOTENAME(s.name) + ''.''
			+ QUOTENAME(OBJECT_NAME(dm_ius.OBJECT_ID)) AS ''dropStatement''
		FROM sys.dm_db_index_usage_stats dm_ius
			INNER JOIN sys.indexes i ON i.index_id = dm_ius.index_id AND dm_ius.OBJECT_ID = i.OBJECT_ID
			INNER JOIN sys.objects o ON dm_ius.OBJECT_ID = o.OBJECT_ID
			INNER JOIN sys.schemas s ON o.schema_id = s.schema_id
			INNER JOIN (SELECT SUM(p.rows) TableRows, p.index_id, p.OBJECT_ID
			FROM sys.partitions p GROUP BY p.index_id, p.OBJECT_ID) p
			ON p.index_id = dm_ius.index_id AND dm_ius.OBJECT_ID = p.OBJECT_ID
		WHERE OBJECTPROPERTY(dm_ius.OBJECT_ID,''IsUserTable'') = 1
			AND dm_ius.database_id = DB_ID()
			AND i.type_desc = ''nonclustered''
			AND i.is_primary_key = 0
			AND i.is_unique_constraint = 0
		ORDER BY (dm_ius.user_seeks + dm_ius.user_scans + dm_ius.user_lookups) ASC; '

	INSERT INTO #dbUnUsedIndex (
					dbID,
					dbName,
					objName,
					idxName,
					idxID,
					UserSeek,
					UserScans,
					UserLookups,
					UserUpdates,
					nbRows,
					dropStatement)
	EXEC sp_executesql  @sqlCmd, N'@dbID INT, @dbName SYSNAME', @dbID, @dbName

    FETCH NEXT FROM cur_dblst INTO @dbID, @dbName
END
CLOSE cur_dblst
DEALLOCATE cur_dblst

SELECT Count(*) FROM #dbUnUsedIndex

SELECT * FROM #dbUnUsedIndex
ORDER BY dbName, objName


 IndexInfo;
GO

For the total number of Indexes, we use this simple query:

SELECT COUNT(*) AS TotalIndexes
FROM dynamicsBC.sys.indexes i
INNER JOIN sys.tables t
ON i.object_id = t.object_id
WHERE i.index_id > 0;

We have 998 unused Index for a total of 19494 Index. This is 5% of the Indexes.
In this case, we will not win a lot. 5% is good but we can have a look because we never known…

The IMPACT

The first impact is on DML INSERT and UPDATE operations.

INSERT

With every insertion, the data is written to the table and several index structures must also be updated, even when one of these indexes is never used by a query.

So we have the following sequence:

INSERT –> write to the table –> update index 1  –> update index 2  –> update index 3  –> update index 4 ….

This is even more costly for this command because, for each operation, the sequence is as follows:

UPDATE

UPDATE –> Delete the old index entry + Create the new entry for each index

The result of all of this is more I/O, more CPU usage and also more entries in the Transaction Log

On heavily used transactional tables, a few unused indexes can account for several per cent of additional load.

The second impact is the storage and the backup

If the unused index represents ~100B of the database.

If 100 GB of indexes are never used, that’s 100 GB backed up unnecessarily, 100 GB restored unnecessarily and, above all, 100 GB stored unnecessarily and just for one environment.

If you have Dev, Test, PreProd & Prod and all in HA… I let you do the calculation but it’s near 1 TB!

The third impact is on the maintenance plan

The following operations must also handle unused indexes:
– Rebuild Index
– Reorganise Index
– CheckDB
– Backups
– Restores

Each additional index extends the maintenance windows…

The ADVISE

You really need to be careful before deleting anything, as an unused index is not necessarily useless.

You should check several factors before you delete unused indexes:
– Full business cycle
– End/Begin of month
– Annual processing
– Reporting
– ETL
– SQL Agent jobs

I generally recommend observing the index between 1 and 3 months before deleting it and without restart. A restart will reset the DMV used for the stats… And always keep the script for recreating the index to hand!

The Green SQL Server DBA Score

Just for fun, we’re going to set up a ‘SQL Server DBA Score’ to use for my tips on the subject:

Conclusion

An unused index is a bit like car that never gets driven:
it takes up space;it costs money;it requires maintenance;but it produces no value.

The Green SQL Server DBA doesn’t just seek to add indexes.
They aim to retain only those that deliver measurable business value.

See you soon for the next one!

L’article Green SQL Server DBA Tips  #1 – Are unnecessary indexes cluttering up your database? est apparu en premier sur dbi Blog.

So, I thought I’d write a little catch-up blog post, to help you to find all LinkedIn Posts!

First, a bit of humour with this image of SQL Server scrolling through LinkedIn and wondering if anyone still loves it… Meanwhile, Power BI and Azure Data Fabric are stealing the show.

Let’s talk about SQL Server, and in particular all tests done on SQL Server 2025:  

SSRS Deprecation – It’s time to rethink your reporting architecture explain you how with our Team, we can help you to go forward!

dbi services’ blog on fire for SQL Server 2025 with this Tips to find all our SQL Server blogs : just Google: site:dbi-services.com/blog SQL Server 2025

Exploring SQL Server 2025 blogs with tests on SQL Server 2025 new features

Time to review your SQLServer licenses with 10% price increase for SQL Server licences, we can help you to optimize your SQL Server Architecture!

SQL Server 2025: AI, Performance… and real-world Lessons with a lot of deep tests and new thinking about  Tuning, Performance & AI

Your SQL Server might be exposed right now is a very important topic because Microsoft put in Augaust and Septembre critical patches in High importance

SQL Server 2025 – What’s new & What’s next? withgood feedback and ideas from SQLBits 2025  in London

It’s time to rethink your data strategy with SQL Server 2025 with the end of DQS, MDS and Synapse Link, it’s  the opportunity to see our expertise in Microsoft Fabic

And also, publications about how we can help beside SQL Server and share these experiences & expertise:

Struggling with rising Azure Data Fabric & Power BI costs? with our experience to help to optimize the cost of your Azure Platform using the BI stack

When M-Files meets SQL Server with our SQL Server & M-Files expertise, we are on the top to help you to configure, customize, optimize, secure  your M-File infrastructure

Continue to follow us in our blogs and linkedIn posts!

L’article SQL Server’s LinkedIn Posts catch-up! est apparu en premier sur dbi Blog.

https://learn.microsoft.com/en-us/ssms

You will see 6 parts in the main panel:

• Overview
• Get Started
• Install
• Customize SSMS
• What’s new in SSMS?
• Troubleshoot

If you have a look on the left menu, you will find more like Copilot in SQL Server Management Studio (Preview) and have a deep dive into this subject:

To follow how to enable and use it, follow the blog of Steven Naudet: Step-by-Step Guide to Enabling Copilot in SSMS

One part I like in the documentation is the “Tips and Tricks” in “Get Started” to be more efficient when you use it:

https://learn.microsoft.com/en-us/ssms/tutorials/ssms-tricks

Have a good start with the new landing page of SSMS!

L’article SQL Server: New SQL Server Management Studio (SSMS)  landing page est apparu en premier sur dbi Blog.

One new feature in preview is the “Schema Design compare” in this last MSSQL extension for Visual Studio Code:

Let’s start and see on a database (db2 in my example):

Et voila, I have my 2 tables created during the test on Schema Compare blog here

Now, I create a new table t3 with some columns:

Very easy to create a table without being a SQL Expert.

As you can see, you have easily access to the option and add some specific input like the size or a default value.

The table t3 is created with a primary key on column c1.

Now, I change my table t2 and want to put c1 as primary key.

To edit the table t2, just click on the pen:

In the edit table, I just check the column c1 as primary key:

And I have my primary key on table t2:

Now, I want do link between my 3 tables (this is named/known as a Foreign Key…)

First between t2 and t3, I go the side of the table t2 and a blue point appears. Take it and go to the table t3

Let’s try between the table t2 and the table t1

Aie! Error message:

• Failed to create a foreign key
• Column ‘c1’ must be a primary key

It’s very good to have this control and information.

This will help a lot of developers…

I will not continue more with the design.
It’s already and really a good tool to design our schema.

One good point is the export button to have the schema design as a picture with 3 formats possibilities svg ,png or jpeg.

No excuse to not do a documentation!

The definition button gives you the design script:

The last button to use is the Publish Changes:

I wait a little bit, and I have the resume of the design change:

I like the checkbox “I have read the summary and understand the potential risks” and I publish.

It’s just a discovery about the Schema design preview.

It will be a good help for developers.

See you soon for the next episode!

L’article SQL Server 2025: Local SQL Server Container – Schema design preview est apparu en premier sur dbi Blog.

One new feature in preview is the “schema compare” in this last extension for Visual Code:

I like new feature and now let’s go for a test!

I create 2 identically databases db1 & db2 with 2 tables and some data inside:

I do a select on both tables on both databases to see if everything is the same:

I run the “schema compare” to be sure I have everything is aligned:

I select the source “db1”, select the target “db2” and click on compare:

After few seconds (due to my small databases), we have the result:

Good! No schema differences were found! It’s a good start…

Now, I play and change a little bit the db1:

• On table t1:
  • Add a column c4
  • Drop a column c1
  • Change the data type of the column c2

• Create a new schema test2

• Transfer the table t2 from schema dbo to scema test2

• Create a new table t3

I run again the schema compare…

This time, we have a result:

I have all my change but like other tools it will delete the table dbo.t2 and create a new one test2.t2. This is not really the same as a schema transfer…

Otherwise, we see the missing table dbo.t2

I will now run the compare in the other way db2 as source and db1 as target:

I see now the delete of what I change on db1, then it’s good and fine except the schema transfer like usual…

I come back to my precedent comparison and this I use the “Switch Direction”:

I test now the script generation:

Et voila, I have my change script:

It will be very nice to use for developers but as you see in my post, you need to be careful with your change (schema change for tables), control and test the script generated before do it on Production databases!

See you soon for the next test on my Local SQL Server Container!

L’article SQL Server 2025: Local SQL Server Container – Schema compare preview est apparu en premier sur dbi Blog.

SQL Connectivity and Drivers – SQL Server | Microsoft Learn

As you can see, you can download, have a quick start and some code samples…

Let’s test on Python!

When I click on “Download”, I have the page for “Python SQL Driver”:

Python SQL Driver – mssql-python (Preview) – Python driver for SQL Server | Microsoft Learn

When I click on “Get Started”, I have the page for “Quickstart: Connect with the mssql-python driver for Python”:

When I click on “Code Sample”, I have the page for “Quickstart: Deploy a Python (Django, Flask, or FastAPI) web app to Azure App Service”:

Very easy to find out and simple to start with a connection to SQL Server from your development tools…

I hope others like Ruby, Spark, … will also come soon!

L’article SQL Server: New connectivity and Drivers landing page est apparu en premier sur dbi Blog.

• Create and manage SQL Server containers locally without Docker commands
• Use SQL Server 2025 by default with vector and AI-ready features
• Auto-connect with a ready-to-use connection profile
• Start, stop, restart, or delete containers from the connection panel
• Automatic port conflict detection and resolution
• Customize container name, hostname, port, and version

See all Preview Features here

First Step: Download and install Visual Studio Code here

Second Step: Download and install MSSQL extension for Visual Studio Code here

You can also directly from Visual Code, download and install the extension:

I choose this easy way…

After few minutes, it’s ready to use:

Third Step: create the Local SQL Server Container

Go to the “SQL Server” tab, select the “Create Local SQL Container” in the “connections” menu:

Oups… I forget to install Docker:

Second Step BIS: Download and Install Docker on my desktop here

Et voila, Docker is installed:

After the restart, I go back to my SQL Server connection in Visual Code.

I see that I’m ready to start…

I can choose the SQL Server image until the version of SQL 2017:

I choose the SQL server 2025 version, enter a password and a profile name:

Check also Accept the Terms & Conditions after reading it of course like every time…

I press the button “Create Container”:

The are three steps:

• Creating Container
• Setting up container
• Connecting to Container

After few minutes, my container is online and ready to be use direclty:

Last Step: Test the connection with a query

I open a query and just do a SELECT @@Version and a SELECT @@Servername:

As you can see, we have the SQL server in version 2025 & Edition Developer on Linux Ubuntu installed without any Docker command to deploy it…

Conclusion

Very easy to install and do the first steps with this new feature and without any skills in Docker command…

I know a lot of developers who want to use it asap!

L’article SQL Server 2025: Local SQL Server Container without Docker Command est apparu en premier sur dbi Blog.

To do this, I will compare SQL 2022 and SQL 2025 using the system view sys.configurations.

I begin with a count(*) to see how many differences I have:

95 configurations for SQL 2022 and 105 configurations for SQL 2025.
Seems that we have 10 new configurations.

Go now to the details with the query on both instances :

SELECT * FROM sys.configurations

I save the result as csv and will see what is double and not:

And finally, I have the 10 new configuration’s possibilities in SQL Server 2025 for the instance:

If I go deeper into these new options, we can already see:

• ADR cleaner lock timeout (s)
  • Default value: 5
  • Description:  Accelerated Database Recovery cleaner lock timeout will be a good complement to already “ADR cleaner retry timeout (min)”,” ADR Cleaner Thread Count” and “ADR Preallocation Factor”
  • Is dynamic: Yes (no restart needed)
  • Is advanced option: Yes
    
• SLOG memory quota (%)
  • Default value: 5
  • Description: SLOG memory quota percentage
  • Is dynamic: Yes
  • Is advanced option: Yes

• max RPC request params (KB)
  • Default value: 5
  • Description: Maximum memory for RPC request parameters (kBytes)
  • Is dynamic: Yes
  • Is advanced option: Yes

• max UCS send boxcars
  • Default value: 5
  • Description: Maximum number of UCS boxcars for sending messages.
  • Is dynamic: No (need a restart of the SQL Server Engine)
  • Is advanced option: Yes

• availability group commit time (ms)
  • Default value: 5
  • Description: Configure availability group commit time in milliseconds for SQL Server only. Will be a good configuration for some of our customers…
  • Is dynamic: Yes
  • Is advanced option: Yes

• tiered memory enabled
  • Default value: 0
  • Description: tiered memory memory-optimized is disabled by default.
  • Is dynamic: No
  • Is advanced option: Yes

• max server tiered memory (MB)
  • Default value: 2147483647
  • Description: Maximum size of server tiered memory (MB)
  • Is dynamic: No
  • Is advanced option: Yes

• external rest endpoint enabled
  • Default value: 0
  • Description: Enable or disable invocations of external REST endpoints
  • Is dynamic: Yes
  • Is advanced option: No

• external xtp dll gen util enabled
  • Default value: 0
  • Description: Enable or disable using external xtp dll generation via HkDllGen.exe
  • Is dynamic: Yes
  • Is advanced option: No

• external AI runtimes enabled
  • Default value: 0
  • Description: Enable or disable using external AI runtimes
  • Is dynamic: Yes
  • Is advanced option: No

These option are not documented yet on the Microsoft website but it will come soon. here the link to the configurations options:

https://learn.microsoft.com/en-us/sql/database-engine/configure-windows/server-configuration-options-sql-server?view=sql-server-ver17

Of course, we will test these options and have best practices to help our customers to have an optimized SQL Server platform.

See you soon for others blogs…

L’article SQL Server 2025: What news on the instance configuration est apparu en premier sur dbi Blog.

You can find the preview in here.

It’s a good opportunity to test this new version before installing it by customers…

After downloading the file vs_SSMS.exe (4,3 MB), start the file to doanload and install it.

For the installation, you have 2 possibilities: “Install while downloading” (the default) or “Download all, then install”.

I chose the last one to install SSMS on a VM for testing…

During the download, you have a link to the release note and see the news features available in this version:

Release notes for SQL Server Management Studio 21 Preview – SQL Server Management Studio (SSMS) | Microsoft Learn

You have also the possibility to install a Visual Studio 2022 Preview.

This version of SQL Server Management Studio is now based on Visual Studio 2022 and supports 64-bit to avoid out-of-memory errors…

Now, start SSMS 21:

The first choice you need to make is the authentication:

• Sign in with Microsoft
• Sign in with GitHub
• Create an account

Or the best option at the begin: “skip for now”

After clicking on “skip for now”, SSMS is running:

I tested first a funny part:

Before this version, the background of SSMS was limited to 3 options:

Now, you have more choice:

I chose the Dark Theme to continue my test…

One of the new options is the Database Scoped Configuration included in the database Properties:

I’m already happy to test this new version of SQL Server Management Studio and will continue to test it…

See you in the next blog post!

L’article New SQL Server Management Studio Version 21 – First Test est apparu en premier sur dbi Blog.

Last night, I followed with Amine Haloui the Future Data Driven Summit 2024 from 3 PM to 2 AM

This event was remote and very easy to follow.

One day with 5 rooms and  more then 55 speakers… Difficult to choose the session between this lot of choice and so interesting.

I will share with you my experience on this shifted day.

The Future Data Driven Summit 2024 begins for me with the session of George Walters:

“Unveiling the Future: Dive into Cloud Databases and Analytics with Fabric”

I really appreciate this session and the 2 announcements:

• Mirroring in Fabric

• Copilot in Microsoft Fabric

After, following Falek Miah and his session: Quest to Delta Optimisation, I go to the session of Bob Ward: Getting started with SQL and AI

Interesting demo to illustrate it with Azure OpenAI Studio:

To know more about SQL Database and AI, go here

After this, Bob presents us the SQL Copilot with a great demo

After this great session, I follow the session of Rob Sewell about The new era of SQL Development -sqlcmd, data api builder,azd and more before the little diner break for us.

After the break, I continue with the session Income statement Co-Pilot with Koyelia Ghosh Roy and Shubham Jindal and continue directly with the session  Modern T-SQL using JSON & RegEx for cloud native developer with Umachandar Jayachandran (UC) and Abhiman Tiwari

This last one was very interesting about  JSON features and T-SQL enhancements in Azure SQL Database.

At 21:20, I follow the session “Be a Better DBA with Database Watcher: A Proactive Approach to Database Monitoring” from Daniel Taylor and Bradley Ball.

At 22:20, It’s time to go see the security topic with the session Your Data Security Isn’t Enough for AI – Yet from James Rice

Great information and examples:

Before the last session, I follow the session Unlocking Data Insights with Kusto Query Language (KQL) with Paresh Motiwala                                                                                           

A very interesting session on the Kusto Query Language and how to use it.

Before going to sleep, I follow the session Empowering AI Applications with Vector Search in Azure Cosmos DB with Leonard Lobel

And now, I havea lot of ideas and tips to search, look and share with my colleagues and customers.

Thanks to dbi services to let me follow these type of event!

L’article Coming back to the Future Data Driven Summit 2024’s Event last night est apparu en premier sur dbi Blog.