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Category: Administration

Trustworthy Databases

Kenneth Fisher asks if you check TRUSTWORTHY settings on your databases:

I wasn’t surprised (although a little disappointed) that out of the 9 people the answered only one person was, and of the rest 5 didn’t even know what TRUSTWORTHY is. I even had one person ask me later. That’s somewhat scary because under the right circumstances if you give me a database with TRUSTWORTHY turned on I can take over your instance. I’m NOT going to show you how but it isn’t terribly difficult.

I’ll admit that I have been a bit non-chalant about TRUSTWORTHY in the past, but turning it on is the smart move.

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Bad Fixes

David Alcock looks at a few common “fixes” which end up causing their own problems:

I’m seeing lots of CXPACKETS waits, how do I fix these?

Bad Advice = Set the maximum degree of parallelism to 1, no more CXPACKET waits!

I’m seeing index fragmentation occur quite frequently on some of my indexes, what should I do?

Bad Advice = Set fill factor on the server to 70, no more fragmentation problems!

I’m worried about TempDB contention. What should I do?

Bad Advice = Set the number of files to the number of cores, no more contention issues!

Read the post for better advice.

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Monitoring For Suspect Pages

John Martin shows us about dbo.suspect_pages:

dbo.suspect_pages is a table that resides in the MSDB database and is where SQL Server logs information about corrupt database pages (limited to 1,000 rows) that it encounters, not just when DBCC CHECKB is run but during normal querying of the database. So if you have a DML operation that accesses a corrupt page, it will be logged here, this means that you have a chance of identifying a corruption in your database outside of the normal DBCC CHECKDB routine.

This is a nice tool we can use to check for corruption.

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Incrementing All Sequences

Mark Broadbent had to increment all of his sequences by 10,000.  Here’s how he did it:

The only problem with this approach is that our database was configured (rightly or wrongly) with approximately 250 sequences! Since we could not be sure which sequences would ultimately cause us problems we decided to increment each one by 10,000.

Not being someone who likes performing monotonous tasks and also recognising the fact that this task would probably need to be performed again in the future I decided to attempt to programmatically solve this problem.

The script isn’t too difficult to understand but let me reiterate his warning:  read the script before you run it, and know exactly what it’s doing before you run it.

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Restoring CDC-Enabled Databases

Mark Broadbent shows us how to restore databases with Change Data Capture enabled:

This automatically poses the question of how it is possible to restore a backup chain with CDC? On a database restore, in order to apply differential backups and transaction logs the NORECOVERY clause is required to prevent SQL Server from performing database recovery.

If this option is required but KEEP_CDC in conjunction with it is incompatible, surely this means point in time restores are not possible for restores that require CDC tables to be retained?

-Wrong!

The answer is a bit surprising, and my guess is that most database administrators are totally unaware of this restoration quirk.

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Identifying Blocked Processes

Priyanka Chouhan talks about identifying and handling blocked processes:

In order to maintain data integrity within the database, locks are used on resources like tables, rows, pages etc. by any process that wishes to use them. This is done to ensure multiple process don’t alter the same resources at one time leading to data inconsistency. When a process wishes to lock a resource, it sends a request to the server and the server grants it. However, when a process requests lock on a resource that has already been locked by another process, the request is denied. The requesting process is thus placed on “hold” until the resource it is requesting for isn’t released. In this situation, the requesting process is called a blocked process, and such a process could put a halt on other subsequent processes and activities scheduled on the server.

Thus identifying a blocked process and releasing it requires a DBA team to check the application database blocking. Additionally, here are some other techniques that may be used to find out which processes are creating a block on the server:

My favorite method, not mentioned, is Adam Machanic’s sp_whoisactive.

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WMF 5 RTM

Windows Management Framework 5.0 is available, says Max Trinidad:

Finally! The Windows Management Framework version 5.0 RTM is available for download for all down level Operating systems: Windows 7, Windows 8.1, Windows Servers 2008 R2, Windows Server 2012, and Windows Servers 2012 R2.

There are several interesting features here.  My favorite one is “Just Enough Administration (JEA)”; after all, who wants too much or too little administration?

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Keep .Net Framework Up To Date

Allan Hirt with a public service announcement:

Microsoft recently published an official .NET team blog post reiterating that .NET Framework versions 4, 4.5, and 4.5.1 will no longer receive security updates, support, or hotfixes as of January 12, 2016. This was first announced back in August of 2014, so it’s not like this is new news, but I can say from experience virtually no one is talking about it. MS’ new post talks more about the upgrade path. To sum it up, you need to install .NET Framework 4.5.2, 4.6, or 4.6.1 to be considered supported when it comes to your .NET Framework version. Security is a real issue for many, and those responsible may not know that your version of .NET Framework could be a possible attack vector. Is your security team aware of this impending problem? How will this affect your version matrices (you do have those, right?)?

This is a cross-cutting concern, and I know a majority of database administrators aren’t directly responsible for .Net Framework patches, but work with whoever is responsible and keep them up to date.

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