Tag Archives: Tips

MAX DOP calculator

Every time I conduct a SQL Server health check, it’s pretty common for me to find wrong configurations at instance level. But one of the most common mistakes I see on the wild, is SQL instances having the “max degree of parallelism” (MAXDOP) set to “1” (single core) , probably this behavior is related to a misconception of how parallelism works or because some DBAs thinks this parameter reduces the “CXPACKET” wait types, who knows …

In order configure MAXDOP properly, DBA’s should read and understand what Microsoft’s has as best practice guideline in the KB# 2806535. This article has a table with the explanation on how to calculate the right value for this configuration:

If you are not familiar with NUMA nodes, logical CPUs or CPUs at all this can be a little bit confusing …

NUMA nodes, CPU specs, logical CPU’s, wait …. WHAT???

I understand, we live in a very busy world where we need to do things quick and make everyone’s work easier. Just imagine having to make this calculation every time you want to change the MAXDOP configuration, you truly need something to make your life easier… enter MAXDOP calculator.

The concept of a MAXDOP calculator was created by a Microsoft field engineer long time ago, the article helps you to set the right value for the MAXDOP configuration, the problem I noticed with this tool is that requires a lot of manual intervention. Anytime you would need some help calculating the correct MAXDOP value you will have to visit the website and provide the input from a couple of queries, there is also an Excel version but I do see the same problem. Don’t get me wrong I think this is a wonderful idea but I do personally don’t like manual stuff.

Based on this need, I have created the same calculator but this time in T-SQL. The same concept but in runs in a SQL environment directly, returning the correct MAXDOP value without using any input as the original approach.

Here is an example of the output:

MAXDOP recommendation at Instance level for also T-SQL statement suggestion to re-configure value

At you can see, it provides you the current and recommended MAXDOP configuration also including the syntax to change it in case it is wrong. For SQL Server 2016 or major, it also returns the MAXDOP value configured at database level.

MAXDOP recommendation at DB and Instance level for SQL Server 2016 (and major) also T-SQL statement suggestion to re-configure MAXDOP

If you want to give try it, you can download the T-SQL script from my GitHub repository.

The requirement to execute this T-SQL script is to have SQLCMD mode enabled in SSMS, you can take a look at my previous post to learn how to enable it.

Please feel free to provide me feedback about this tool, stay tuned for more DBA mastery tips!

I’m very experienced multi platform Database Administrator (Oracle, SQL Server, MySQL), working for large scale US based companies and some other companies around the world.

I have multiple Microsoft SQL Server certifications under my belt (MCP, MCTS, MCSA, MCSE), and currently taking the Microsoft Data Science program.

Cleaning up Query Store data after database restore

Query Store is a very powerful tool for performance tuning, if you are not using it already you should!! It will save you a lot of time and effort because it makes the performance troubleshooting easy for DBA’s. It helps you to quickly find performance differences caused by query plan change or a query regression after an upgrade.

One of the caveats of using this tool is that uses space from the PRIMARY file group when enabled, that means if the database is restored to another environment the Query Store data will be restored as well making your database restored version a little bit bigger and containing information that is probably not relevant for a development environment (unless you are doing a troubleshooting).

In case you have recurrent tasks to restore a production database in a different environment and you are not interested on having the Query Store data on your restored version, there is a way to cleanup the Query Store data for good.

Here is the T-SQL script you have to use:

ALTER DATABASE "MyDB" SET QUERY_STORE CLEAR;
ALTER DATABASE "MyDB" SET QUERY_STORE (OPERATION_MODE = READ_ONLY);
ALTER DATABASE "MyDB" SET QUERY_STORE = OFF;

As you can see, with this simple T-SQL script you are not only cleaning up all the Query Store data but also disabling Query Store putting it in read only mode.

Stay tuned for more DBA mastery tips!

I’m very experienced multi platform Database Administrator (Oracle, SQL Server, MySQL), working for large scale US based companies and some other companies around the world.

I have multiple Microsoft SQL Server certifications under my belt (MCP, MCTS, MCSA, MCSE), and currently taking the Microsoft Data Science program.

SQLCMD mode in SSMS

I really like Microsoft philosophy nowadays, they are putting a lot of time developing good open source tools like SQLCLI, SQLOps and Visual Studio Code, those tools has something in common “a built-in terminal” a multi-platform and code geek like me really appreciate those details. It is pretty neat to use the built-int terminal to do stuff without leaving your development enviroment.

This functionality is also available on SSMS (in some way), it is called SQLCMD mode. This feature allows you to interact directly with Windows command line without leaving your SSMS environment, for example long time ago I had the need to generate a SQL file from an output of a query, I knew I can use SQLCMD for such thing but I didn’t want to create an external script to be call from command … so I did my research and figure out SQLCMD mode in SSMS can do such thing without having to run outside SSMS.

Go to Query in main menu, then click SQLCMD mode to enable it

Here is how you can enable SQLCMD mode in SSMS:

Alright! so, now let’s do a quick example. Imagine you don’t want to lose the list of roles assigned to all your database users for a specific database, in order to script out the roles we will run a query and generate an output directly to Windows having the T-SQL script ready to run when needed.

Here is the T-SQL code:

BEGIN
    SET NOCOUNT ON
    :OUT F:\MyDB_Roles.sql

    DECLARE @Role varchar(255)
    SET @Role= '%'

    -- Add Users to roles
    SELECT
        'EXEC sp_addrolemember ''' + RTrim(r.name) + ''',''' + RTrim(Coalesce(l.name,u.name)) + '''' as '-- Add Role Users'
    FROM dbo.sysusers u
        INNER JOIN sysmembers m
        ON u.uid = m.memberuid
        INNER JOIN sysusers r
        ON m.groupuid = r.uid
        LEFT OUTER JOIN master.dbo.syslogins l
        ON u.sid = l.sid
    WHERE r.issqlrole = 1
        AND u.name <> 'dbo'
        AND r.name LIKE '%'
    ORDER BY r.name,u.name

    PRINT '-- End of script'
END

Note the third line, I’m using the :OUT command which will take care of redirecting the query result into a SQL file within Windows:

:OUT F:\MyDB_Roles.sql

Once the query is executed, here is how the SQL File output file looks from Visual Studio code:

As you can see this is a normal T-SQL script generated from SSMS, it contains the roles we wanted to script out from our database. As you may realize by now this is a very handy option in SSMS, and to be fair with SQLCMD mode this is just a simple use case there is more scenarios where this SSMS functionality can help you to achieve very neat things.

For more information about other parameters for SQLCMD,  please check this link from Microsoft docs.

Stay tuned for more DBA mastery tips!

I’m very experienced multi platform Database Administrator (Oracle, SQL Server, MySQL), working for large scale US based companies and some other companies around the world.

I have multiple Microsoft SQL Server certifications under my belt (MCP, MCTS, MCSA, MCSE), and currently taking the Microsoft Data Science program.