SQL Server 2016 SP2 CU2 Available

On July 16, 2018, Microsoft released SQL Server 2016 SP2 CU2, which is Build 13.0.5153.0. There are 21 fixes in the public fix list, including a number of fixes in the SQL performance, SQL Engine, and High Availability fix areas.

Microsoft has also released SQL Server 2016 SP1 CU10, which is Build 13.0.4514.0. There are also 21 fixes in the public fix list, including a number of fixes in the High Availability and SQL Engine fix areas. I think you should be on The SQL Server 2016 SP2 branch by now, or as soon as possible, but the SP1 branch is still supported.

I want to convince more people to try to keep their SQL Server instances up to date with Cumulative Updates. If you do the proper testing, planning and preparation, I think the risks from installing a SQL Server Cumulative Update are quite low (despite the occasional issues that people run into).

If you install a Cumulative Update or Service Pack on a Production system the day it is released, after doing no testing whatsoever, and then run into problems (and don’t have a plan on how to recover), then I don’t have that much sympathy for you.

On the other hand, if you go through a thoughtful and thorough testing process, and you have a plan for how you will install the CU, and how you would recover if there were any problems, then you are much less likely to have any problems. You are also much more likely to avoid the issues that are fixed by all of the included fixes in the new build of SQL Server. You have done your job as a good DBA.

Finally, Microsoft has changed their official guidance about whether you should install SQL Server Cumulative Updates. As they say, “we now recommend ongoing, proactive installation of CU’s as they become available”.

T-SQL Tuesday #104: Code I Have Written That I Would Hate to Live Without

Bert Wagner (b/t) is hosting T-SQL Tuesday #104. The invitation is to write about code you’ve written that you would hate to live without. For me, this is almost a no-brainer!

My DMV Diagnostic Queries represent a lot of code that I would hate to live without. I use them on a daily basis to gather information about SQL Server instances and databases and to help more quickly understand what configuration and performance issues they have. I’ve been publicly posting these queries since 2009, but I actually started developing them for my own personal use back in 2006. The story about how they came about is kind of interesting…

Back in about August of 2006, I was the sole DBA for NewsGator, which was (at that time) an RSS aggregation company. Our main product/service was the ability to let people “subscribe” to RSS feeds for web sites and blogs, and then have us download the RSS feeds of those sites. We would also manage the “read state” of the RS feeds that you subscribed to, so that as you read through your subscribed content and marked posts as read, we would synchronize your progress across different devices.

I had only been at the company about three months, and we had recently migrated from 32-bit SQL Server 2000 to 64-bit SQL Server 2005 SP1 on a two-node FCI running on new hardware. Performance had been pretty good since the migration, and it was about 4:30PM on a Friday afternoon, when I started making some final quick checks of the health of my instance before getting ready to leave for the weekend.

I noticed that my CPU utilization was running about 90-95%, which was much higher than normal. I tried a few of my standard DBA tricks (at that time) to correct the issue, such as running sp_updatestats, running DBCC FREEPROCCACHE, etc. with no real improvement. I even took the emergency step of “shutting down” the content servers (which were application servers that downloaded the RSS feeds, that typically generated about 90% of my database load). This had no appreciable effect on my CPU utilization.

By now, I was getting worried, since we had a problem that I did not immediately know how to diagnose and correct. By this time, our support team and many of the senior executives in the company were aware that we had a problem because our applications were starting to time out and throw errors. I had a literal parade of different people coming to my desk asking some variation/combination of “What’s wrong with the database?” or “What can we do to help?”.

This got so bad that the CTO/Founder of NewsGator (Greg Reinaker) grabbed a large rolling whiteboard, and wrote something like “Glenn knows there is a problem. He is working on it. Please leave him alone”, which was actually pretty helpful.

So after some time, it ended up being just me and the best developer on the Platform Team (Jeff Tingley) staying late into the night and next morning, on a call with Microsoft Premier Support trying to diagnose and troubleshoot the issue. Eventually, we figured out that our problem was mainly caused by parameter sniffing in one stored procedure where we were getting one very inefficient plan stuck in the plan cache.

The short-term fix was to use a local variable to store an input parameter for that stored procedure to disable parameter sniffing for that stored procedure, and to periodically recompile a few other stored procedures that were also part of the problem. Jeff and I finally left around 3AM, with the system being relatively stable. I was exhausted from the time and the stress of feeling like the fate of the company rested on my shoulders. I was convinced that I was in big trouble and was possibly going to be fired since it had taken us so long to figure out the problem. Little did I know…

As it turned out, my boss’s boss decided to give both Jeff and I a $500.00 bonus, plus we got a big round of applause at a company meeting the next Monday (which I appreciated much more).

This incident was the genesis of my DMV Diagnostic queries. I never wanted to be in that situation again! Anytime there was any application slowdown, people always assumed that it was a database problem (which was not always the case). Having a set of queries that I could run to figure out what was going on with the database and database server was the key to being able to answer the “What’s wrong with the database?” question.

Many thousands of people around the world use my queries on a regular basis, and seem to find them very useful, at least based on the feedback I have gotten over the years. Now you know the story of how they came into being.

Figure 1: Link to Invitation Post

SQL Server Diagnostic Information Queries for July 2018

This month, there are improvements to seven of the the SQL Server 2012 and newer versions of the queries, with a new column that shows whether there is a missing index warning in the cached query plan. A reader named Håkan Winther made this useful suggestion.

I have also developed a T-SQL script that you can use to check whether your instance of SQL Server has been patched to mitigate against the Spectre/Meltdown CPU vulnerability. This works for SQL Server 2008 through SQL Server 2017, for on-premises and cloud-based VM (IaaS) usage. You can get the query for this here.

I often make additional minor updates to the queries periodically during the month, so if you are in doubt, downloading the latest version is always a good idea.

Rather than having a separate blog post for each version, I have just put the links for all eight major versions in this single post. There are two separate links for each version. The first one on the top left is the actual diagnostic query script, and the one below on the right is the matching blank results spreadsheet, with labeled tabs that correspond to each query in the set.

Here are links to the latest versions of these queries for Azure SQL Database, SQL Server 2017, 2016 SP2, 2016, and 2014:

Azure SQL Database Diagnostic Information Queries

Azure SQL Database Blank Results Spreadsheet

SQL Server 2017 Diagnostic Information Queries

SQL Server 2017 Blank Results Spreadsheet

SQL Server 2016 SP2 Diagnostic Information Queries

SQL Server 2016 SP2 Blank Results Spreadsheet

SQL Server 2016 Diagnostic Information Queries

SQL Server 2016 Blank Results Spreadsheet

SQL Server 2014 Diagnostic Information Queries

SQL Server 2014 Blank Results Spreadsheet

Here are links to the most recent versions of these scripts for SQL Server 2012 and older:

Since SQL Server 2012 and older are out of Mainstream support from Microsoft (and because fewer of my customers are using these old versions of SQL Server), I am not going to be updating the scripts for these older versions of SQL Server every single month going forward.  I started this policy a while ago, and so far, I have not heard any complaints.

SQL Server 2012 Diagnostic Information Queries

SQL Server 2012 Blank Results Spreadsheet

SQL Server 2008 R2 Diagnostic Information Queries

SQL Server 2008 R2 Blank Results Spreadsheet

SQL Server 2008 Diagnostic Information Queries

SQL Server 2008 Blank Results Spreadsheet

SQL Server 2005 Diagnostic Information Queries

SQL Server 2005 Blank Results Spreadsheet

The basic instructions for using these queries is that you should run each query in the set, one at a time (after reading the directions for that query). It is not really a good idea to simply run the entire batch in one shot, especially the first time you run these queries on a particular server, since some of these queries can take some time to run, depending on your workload and hardware. I also think it is very helpful to run each query, look at the results (and my comments on how to interpret the results) and think about the emerging picture of what is happening on your server as you go through the complete set. I have quite a few comments and links in the script on how to interpret the results after each query.

After running each query, you need to click on the top left square of the results grid in SQL Server Management Studio (SSMS) to select all of the results, and then right-click and select “Copy with Headers” to copy all of the results, including the column headers to the Windows clipboard. Then you paste the results into the matching tab in the blank results spreadsheet.

About half of the queries are instance specific and about half are database specific, so you will want to make sure you are connected to a database that you are concerned about instead of the master system database. Running the database-specific queries while being connected to the master database is a very common mistake that I see people making when they run these queries.

Note: These queries are stored on Dropbox. I occasionally get reports that the links to the queries and blank results spreadsheets do not work, which is most likely because Dropbox is blocked wherever people are trying to connect. I am not planning on moving these to Github any time soon.

I also occasionally get reports that some of the queries simply don’t work. This usually turns out to be an issue where people have some of their user databases in 80 compatibility mode, which breaks many DMV queries, or that someone is running an incorrect version of the script for their version of SQL Server.

It is very important that you are running the correct version of the script that matches the major version of SQL Server that you are running. There is an initial query in each script that tries to confirm that you are using the correct version of the script for your version of SQL Server. If you are not using the correct version of these queries for your version of SQL Server, some of the queries are not going to work correctly.

If you want to understand how to better run and interpret these queries, you should consider listening to my three related Pluralsight courses, which are SQL Server 2014 DMV Diagnostic Queries – Part 1SQL Server 2014 DMV Diagnostic Queries – Part 2 and SQL Server 2014 DMV Diagnostic Queries – Part 3. All three of these courses are pretty short and to the point, at 67, 77, and 68 minutes respectively. Listening to these three courses is really the best way to thank me for maintaining and improving these scripts…

Please let me know what you think of these queries, and whether you have any suggestions for improvements. Thanks!