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Category: Administration

Auditing Logons Using Extended Events

Published 2020-04-21 by Kevin Feasel

Jason Brimhall dumps a server-side trace in favor of extended events:

Some time ago, I wrote an article for SQL Server 2008 to help determine the use of the server since SQL Server 2008 was reaching End Of Life. In that article, I shared a reasonable use of server side trace to capture all of the logon events to the server. Afterall, you have to find out the source of connections and who is using the server if you need to migrate it to a newer SQL Server version. You can read that article here.

Soon after, from various sources, I received requests on how to perform a logon audit using the more preferred, robust, venerable, awesome tool called Extended Events (XEvents). In response, I would share a login audit session to each person. In this article, I will share my login audit solution and give a brief explanation. I use a solution like this on more than 90% of my client servers and I find it highly useful.

Click through to see how.

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Operational Database Management Tools in Cloudera Data Platform

Published 2020-04-20 by Kevin Feasel

Gokul Kamaraj, et al, describe tools available to DBAs in the Cloudera Data Platform:

Cloudera provides multiple mechanisms to allow backup and recovery, including:

– Snapshots
– Replication
– Export
– CopyTable
– HTable API
– Offline backup of HDFS data

These can be run manually or scheduled using Replication Manager. Backups can also be moved to other instances of the OpDB or alternate storage targets such as AWS S3 or Azure ADLS gen 2.

Even in the Platform-as-a-Service world, there’s still plenty of scope for database administration.

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Diagnosing Out of Memory Failures with SQL Server 2017

Published 2020-04-17 by Kevin Feasel

Lonny Niederstadt had a curious issue:

When [Max Server Memory] can be attained by SQL Server, [Target Server Memory] will be equal to [Max Server Memory].  If memory conditions external to SQL Server make [Max Server Memory] unattainable, [Target Server Memory] will be adjusted downward to an attainable value. As workload is placed on the system, [Total  Server Memory] grows toward [Target Server Memory].  That’s typical, expected behavior.

In this case, the story stays boring until after the following midnight.  There wasn’t enough workload to drive much growth of [Total Server Memory] until about 2:15 am, after which [Total Server Memory] grew fairly rapidly.  [Total Server Memory] reached a plateau between 3:00 am and 3:15 am, and then stepped slightly down later.  [Target Server Memory] was never attained.  That’s curious.

Indeed it is. Read the whole thing. And, given that it is labeled as Part 1, stay tuned for Part 2.

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Querying Database and Log File Sizes with T-SQL

Published 2020-04-17 by Kevin Feasel

Allen White takes us through an easy technique to check database and log file sizes:

As a consultant, I have to be able to quickly spot problems, and one of the problems I frequently find is transaction log files that are incorrectly sized.

There are two catalog views in the master database which make this easy to do – sys.master_files and sys.databases. The sys.master_files view contains the database and individual file names, and the data_space_id column always has a value of 0 for the log file. The size column returns the value in 8KB pages, so we have to multiply the column by 8, then divide by 1024 to get the size in megabytes (MB).

Click through for the demo.

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Bulk Migration of Data and Log Files in SQL Server

Published 2020-04-16 by Kevin Feasel

David Fowler shows how you can change file paths for all of your databases in one fell swoop:

You’ve got a SQL Server with a few hundred databases on it (to be honest it doesn’t even need to be quite that many) and you need to move all the data and log files to a new location. Perhaps you’re going to be migrating onto a new, shiny SAN or maybe your disks are just about full and you need to shift a bunch of the files off somewhere else.

The first thing that you’re going to need to do is change the paths of the files in SQL. That’s easy enough to do with an ALTER DATABASE statement.

ALTER DATABASE SQLUndercover MODIFY FILE (NAME SQLUndercover_Log, FILENAME = 'F:\SQLLogs\SQLUndercover_Log.ldf'

But that’s going to get very tedious very quickly if you’ve got to do that for a whole lotta databases. So to help out, I thought I’d share a little script that I’ve been using for a while (or a variation on it at least) to make the process far easier and generate all the ALTER statements for you.

Click through for the script as well as a bit of advice around the actual moving of the files.

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CHECKDB Matters in the Cloud Too

Published 2020-04-16 by Kevin Feasel

Daniel Janik takes us through an ordeal related to CHECKDB on an Azure Managed Instance:

This is crazy! What now? Open at ticket with MSFT? This seemed the only choice and what was the root cause? Apparently in Azure Managed Instances, Microsoft will check databases for corruption and will take the database offline if detected.

When in this special offline state there’s no way to access the database and Microsoft must be contacted. You can’t set the DB in recovery mode or change it to ONLINE. Microsoft does “contact” someone to notify that the database was taken offline due to corruption but if you work at a larger company this notification may never reach the right people.

Read on to see what Daniel ended up doing and some tips on making the process smoother.

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The Observer Effect when Troubleshooting

Published 2020-04-16 by Kevin Feasel

Dmitri Korotkevitch reminds us that monitoring has a cost:

It is relatively easy with the tools – you can detect those inefficiencies just by looking at the expensive queries in the system. This is not always the case, however, with other technologies, like with monitoring done by Extended Events. They can stay almost invisible in the system, especially if targets are keeping up and don’t generate waits.

Let me show you an example and create xEvent session that captures queries that were executed in the system. This is very common one, is not it? 

Click through for the example and what happens under heavy load.

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Avoiding the sp_ Prefix in Stored Procedures

Published 2020-04-16 by Kevin Feasel

Randolph West takes an Erik Darling video one step further:

Erik Darling, of Erik Darling Data (blog | Twitter) recently posted a very interesting video (my YouTube playlist is all Erik Darling Data videos and Honest Trailers). In this video he demonstrates an easily repeatable issue about naming weirdness and the CREATE OR ALTER PROCEDURE syntax, with stored procedures starting with sp_. The video is 141 seconds long, so go watch it. I’ll wait.

Cool. As many of my readers know — because you’re intelligent and attractive in equal measure — Microsoft does not want us using sp_ for stored procedure prefixes for general use, because it’s kind of reserved:

Read on for some fun with system-like objects.

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Finding the xp_cmdshell Running User

Published 2020-04-15 by Kevin Feasel

Steve Stedman shows which user account actually runs commands when you use xp_cmdshell:

When you execute xp_cmdshell SQL Server runs a command at the operating system level similar to the old DOS prompt, or CMD shell. There are many security concerns and misconceptions about xp_cmdshell as documented in an earlier post.

The purpose of this post is not to debate whether xp_cmdshell is safe or not, but instead to show what user commands sent to xp_cmdshell are being run as.

Read on for a sample script.

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Installing SSMS on Servers Running SQL Server?

Published 2020-04-15 by Kevin Feasel

Andy Mallon says yes, install SQL Server Management Studio on those servers running SQL Server instances:

“But wait, Andy. That’s not a best practice!” you say?

The pseudo best practice of “don’t install SSMS” is a misguided one–advice that I even fell into repeating in the past. However, that’s actually proposed solution to a best practice, rather than being itself a best practice.

I agree with Andy wholeheartedly on this.

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