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Day: April 22, 2016

Where Was I?

Published 2016-04-22 by Kevin Feasel

Shane O’Neill shows how to see the queries which were run in Management Studio:

Suddenly you’re not sure if you really ran the SELECT statement at all.
Maybe you ran the insert statement and 2089 rows were marked to never be seen again!
Or maybe that other table only had 2089 rows in it and you’ve now deleted every one!!

Now this blog post is not going to deal with fail-safe’s for preventing those scenarios because 1) you should already know how to do that, and b) if you don’t know, then maybe back away until you research it… It’s only going to deal with a nice little way you can figure out what it was that you just ran.

I don’t think this will go into my everyday processes, but it’s handy to have when you absolutely need to make sure you’re running the correct line in a script.

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Messing With Statistics

Published 2016-04-22 by Kevin Feasel

Erik Darling shows how to fake stats:

One thing I’ve found is that the inflated counts don’t seem to change anything for Identities, or Primary Keys. You’ll always get very reasonable plans and estimates regardless of how high you set row and page counts for those. Regular old clustered indexes are fair game.

Some really interesting things can start to happen to execution plans when SQL thinks there’s this many rows in a table. The first is that SQL will use a rare (in my experience) plan choice: Index Intersection. You can think of this like a Key Lookup but with two nonclustered indexes rather than from one nonclustered index to the clustered index.

This is very useful when you don’t have many rows in dev, can’t put many rows in dev, and can’t restore a stats-only database from prod.

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More On String Splitting

Published 2016-04-22 by Kevin Feasel

Aaron Bertrand has a follow-up post on STRING_SPLIT():

So here, the JSON and STRING_SPLIT methods took about 10 seconds each, while the Numbers table, CLR, and XML approaches took less than a second. Perplexed, I investigated the waits, and sure enough, the four methods on the left incurred significant LATCH_EX waits (about 25 seconds) not seen in the other three, and there were no other significant waits to speak of.

And since the latch waits were greater than total duration, it gave me a clue that this had to do with parallelism (this particular machine has 4 cores). So I generated test code again, changing just one line to see what would happen without parallelism:

There’s a lot going on in that post, so I recommend checking it out.

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IT Pro Cloud Essentials Program

Published 2016-04-22 by Kevin Feasel

Grant Fritchey talking about a new Microsoft program:

You need to start working on adding Azure knowledge to your skill set. If you have access to an MSDN license, getting into Azure is easy because of the credits available. However, not everyone works for a company that provides MSDN or has purchased a license. In that case, getting into Azure, just for testing and learning could be expensive (I frequently “spend” $150/month with my MSDN credits). However, Microsoft is very serious about getting everyone moved into this space. They’ve launched a new free program called IT Pro Cloud Essentials. Not only does it give you Azure credit, but you also get access to O365, another set of skills and understanding you need to acquire.

Also check out their Visual Studio Dev Essentials program.  Its Azure credit is only $25 a month, but offers you SQL Server 2014 (and will offer 2016) Developer Edition.

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Finding Nested Stored Procedures

Published 2016-04-22 by Kevin Feasel

Michael J. Swart has a script to find nested stored procedures:

Adventureworks seems just fine to me. Only four instances of procedures calling procedures. I looked at the database I work with most. Hundreds of procedures (representing 15% of the procedures) call other procedures. On the other end of the spectrum is Stackoverflow. I understand that they don’t use stored procedures at all.

Check out the comments for more notes.

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Truncating Log Files

Published 2016-04-22 by Kevin Feasel

Sean McCown has a script to truncate log files:

I want to show you a great piece of code to truncate and shrink all your log files. The biggest question you always ask is why should you shrink your log files? It’s been drilled into everyone’s head that shrinking log files is bad because you can cause too many VLFs, and of course there’s the zeroing out that happens when they grow.
OK, so let’s answer that question. There are a couple reasons you’d want to shrink all the files to a small size.

Regularly shrinking log files in production isn’t a particularly great thing, but as Sean points out, there are valid reasons for doing this.

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