Normally, when you use Transparent Data Encryption (TDE) to secure your database at rest, you can’t get backup compression. Encrypted data basically looks like random data, and random data doesn’t compress well. SQL Server 2016 introduced the ability to compress your TDE databases. Yay! Unfortunately, it has bugs that can leave you unable to restore…
Step By Step When you think about setting up maintenance, a persistent fear is that tasks may step on each other. You probably don’t want backups and CHECKDB and statistics maintenance running at the same time as statistics maintenance (notice I didn’t say index maintenance, here, because you’re smart and you skip it?). You may…
Remember that very first day when you officially became a Database Administrator? Remember how the Senior DBA sat you down and gave you clear, specific instructions on how to handle SQL Server? No? You don’t remember that? That’s because it rarely happens. You just happened to be the one standing closest to the database server…
Funny thing The human body is pretty good at adaptation. When you get sick or injured, your body responds and (most of the time) heals itself up. When you stress your body in a certain way, over time, your body will feel less stressed by the same level of that activity. If you do 10…
I love Query Plans No seriously, I love digging into query plans. Even writing XQuery to dig into them in sp_BlitzCache. I was both honored and horrified to take over development of it from Jeremiah. It’s a beast, but it’s my kind of beast. At around 4500 lines of code, when you want to make…
Brent says: “How many people are in the on-call rotation with me, and can I give them each a technical test?” Once you get out of the on-call rotation, it’s really hard to go back to the electronic tether. I’d be willing to do it, but only if there are other sharp people to share…
In my performance training class, people get really excited when I cover filtered indexes, computed columns, and indexed views. Then they get a really strange expression on their face when I talk about one of the biggest drawbacks: if your connection options aren’t set correctly, your delete/update/insert (DUI) operations will fail. That gave me a really…
CURRENT_YEAR() Here it is, 2017. A full 20 years since SQL Server 7. Back then, there was a developer named Nick. Nick was on the development team, and apparently the query-costing-magic development was done on his machine. All of it. The magical metric was that for every second a query ran, it would cost another…
When I first look at a server, I want to know how busy it is, where its bottlenecks are, what is SQL Server waiting on and many other things. Batch Requests/sec is one of the data points that is used to measure how busy a server is. WHAT IS BATCH REQUESTS/SEC? Batch Requests/sec is a performance counter…
I recently saw a server with trace flag 2453 configured. I hadn’t come across this trace flag before, so I did a little research. Microsoft says it allows “a table variable to trigger recompile when enough number of rows are changed”. This can lead to a more efficient execution plan. Trace flag 2453 is available…
Way back in 2016 I wrote about what to do if sp_BlitzFirst warns about high compiles. During GroupBy, Adam Machanic gave a great talk on new features in SQL Server 2016. It reminded me of a blog post I wanted to write about one common culprit of high compiles: Multi-Statement Table Valued Functions. Leaving aside…
All the cool kids Know that when you’re trying to figure out why a stored procedure is slow sometimes, you should use a temporary stored procedure instead of pulling the code out and running it ad hoc. We frequently point people to Erland Sommarskog’s “Slow in the Application, Fast in SSMS“, because it’s an excellent…
Of Course Not Nothing survives in tempdb. But this kind of stinks for those of us who don’t want certain things created in there. In my case, when I’m working on Blitz scripts, I have a terrible habit of accidentally re-creating the procs in user databases. Usually whichever I’m building test data in, like Stack…
Whenever I work with SQL Server, I’m amazed at how many ways there are to influence its behavior. For example, take the maximum degree of parallelism for a query. Just offhand, I thought of ten different ways you can tweak it: 1. At the server level with SSMS. In SSMS, right-click on the server, click Properties, Advanced,…
People often don’t give this thought Which is a shame, because I see people sticking fairly large amount of data into temp tables. On the rare occurrence that I do see them indexed, it’s a nonclustered index on a column or two. The optimzer promptly ignores this index while you select 10 columns and join…
I often hear companies say, “We can never ever go down, so we’d like to implement Always On Availability Groups.” Let’s say on January 1, 2016, you rolled out a new Availability Group on SQL Server 2014. It’s the most current version available at the time, and you deploy Service Pack 1, Cumulative Update 4 (released…
I like science fiction Not enough to go to conventions, or memorize every line, but I have some opinions on things. Dune is probably my favorite series of stories in the genre. Yes, I think Paul would beat Luke in a fight. Sorry, Star Wars people. He’s just kind of a wimp. Throw grenade, digress One…
We’ve already covered how to log activity using sp_WhoIsActive, but I wanted to share how I’ve seen it done in the wild. The difference between the two methods is that this version logs everything to the same table and is for continuous activity logging (scheduled job), whereas the other version uses a new table each time…
If you’re using SQL Server 2016’s awesome new feature, Query Store, there’s a new bug with automatic cleanup. Books Online explains: Automatic data cleanup fails on editions other than Enterprise and Developer. Consequently, space used by the Query Store will grow over time until configured limit is reached, if data is not purged manually. If…
Let’s start with definitions Many SANs have caching built in. What kind of cache is important, because if you’re dealing with non-SSD storage underneath, you could be waiting for a really long time for it to respond. Let’s start with some definitions of the most popular caching mechanisms available for SANs. I’m not going to…
