Guess who I’m going to give you three queries, and you have to guess what the output will be before you run them. Here they are: DECLARE @DatabaseName NVARCHAR(256) = N” SELECT @DatabaseName = d.name FROM sys.databases d WHERE d.name = ‘master’ AND compatibility_level = 130 ORDER BY d.database_id PRINT @DatabaseName SELECT @DatabaseName = d.name…
SQL Server has three ways to get execution plans from the plan cache: sys.dm_exec_query_plan – around since SQL Server 2005 sys.dm_exec_text_query_plan – added in 2005 SP2 sys.query_store_plan – new in SQL Server 2016 And there’s an important problem with the first one. To show it, let’s take one of my many bad ideas, building queries that take 12+…
I hate that you can do this Here’s the thing: I’m mostly writing this because I didn’t know you could do it. But it’s cool, because it’ll reinforce some other concepts, and I’ll show you why you shouldn’t do it. I’m talking, of course, about index hints. To be more specific, hinting multiple indexes on…
This is a post because it surprised me It might also save you some time, if you’re the kind of person who uses NOLOCK everywhere. If you are, you’re welcome. If you’re not, thank you. Funny how that works! I was looking at some code recently, and saw a CTE. No big deal. The syntax…
March comes in like a 40 of Steel Reserve and leaves like your memory of the night after drinking a 40 of Steel Reserve. Get it here! sp_Blitz Improvements — #758 and #756 We made it less scary to run on Express Edition. Why? Because running Express Edition is scary enough. Coded by @Totty1973 and…
I Always Enjoy Reminiscing And that header is a lie. I do enjoy thinking about stuff I used to have to do at work, because I don’t have to do it anymore. While we mostly gripe about the on-call stuff, the late night maintenance windows, etc., we don’t usually talk about the goofy stuff we’ve…
Don’t make me regret publishing this This really will take a server down immediately. You can restart it, as we learned during DBA Days, but… If you also go ahead and make this an Agent job that runs at startup, there are additional challenges. Like every time Agent starts up, your server goes down. Score…
I love a bad idea I mean, just look at me. I’m covered in them! So when Brent wanted to randomly make his server act crappy, I wrote a script for it. Usual caveats here. Don’t run this in production. I’m not responsible for anything you do after you hit copy and paste. In fact,…
I happened to be in Seattle this week after finishing up an Alaska cruise, and I had the chance to sit down with some of the PMs responsible for upcoming SQL Server features. It turns out they’re already deep in development with some truly revolutionary capabilities. Now, I probably shouldn’t be sharing these with you,…
Let’s say, just theoretically, you wanted to demo a query that takes SQL Server a long time to compile. And in order to make SQL Server’s job tougher, you wanted to create the maximum number of indexes possible on a table. You might do something like this: SELECT TOP 999 ‘CREATE INDEX [IX_’ + c1.COLUMN_NAME…
As part of an experiment, I needed to build a really long query. (Don’t ask.) From another recent experiment, I know that SQL Server won’t let a query return more than 65,535 columns. I set about writing a one-line query that would return 65,535. I’m a big fan of writing the simplest reproduction scripts possible –…
Somewhat different than a sex bomb, a fork bomb is a denial-of-service attack that just starts a process that replicates itself, thereby starting more and more processes until the service goes down. Wikipedia’s fork bomb page lists examples on most operating systems (including Windows). I’ve always found fork bombs funny because of their elegant simplicity, so…
Every now and then, we put on our bad idea jeans in the company chat room and come up with something really ill-advised. We should probably bury these in the back yard, but…what fun would that be? Bad ideas are the most fun when they’re shared. One day, after seeing enough horrific but well-meaning indexes created…
Say you’re at Dell DBA Days, and you want to build a really ugly query, fast. You want to generate a StackOverflow database query that will take a long time to compile, and maybe demand a huge amount of memory to run, but not actually take any time to execute. You might start by building…
I travel a lot, and I’ve seen a lot of things, but even I was surprised this week when I sat down in a Cracker Barrel Restaurant that had the oddest soundtrack. It turns out there’s an entire sub-genre of country music that specializes in database songs. While I was sitting there eating my Uncle…
Last August, we got the team together in person for Dell DBA Days. We ran all kinds of interesting experiments with SQL Server, and shared the results with you via live webcasts. You can watch our recorded episodes from last year – I’d highly recommend the last one, Watch SQL Server Break and Explode. Erik showed…
No, not #tables – actual tables. Here’s how: USE tempdb; GO /* This one is only available during my session: */ CREATE TABLE #myTempTable (ID INT IDENTITY(1,1), Stuffing VARCHAR(100)); GO /* This one is global, meaning it’s available to other sessions: */ CREATE TABLE ##myTempTable (ID INT IDENTITY(1,1), Stuffing VARCHAR(100)); GO /* You can create…
I remember the first time I used SQL Server 2005. I was a database administrator working on a new-build data warehouse project in Miami. Both our data warehouse and SQL Server 2005 were looking like they were going to come out at the same time, and I kept hoping I could make the timing work. SQL…
Microsoft announced today that the forthcoming SQL Server 2016 version won’t just run on Linux – it will only run on Linux. “When we started developing the Linux port of SQL Server, we weren’t really serious about it at all,” confessed Mark Souza, lead documentation author for the project. “But after a couple of weeks, we realized how good…
