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Author: Kevin Feasel

PCI Compliance

Published 2016-06-16 by Kevin Feasel

Denny Cherry reminds us that SQL Server 2005 is no longer PCI compliant:

If you are running a PCI compliant system on SQL Server 2005 you are going to fail your next audit. One of the audit requirements is that the vendors must support the version of your software which you are running on. As Microsoft no longer offers support for SQL Server 2005 that’s going to cause you to fail your next PCI audit.

Microsoft’s serious about sunsetting old versions of SQL Server, and at this point, there have been five versions of SQL Server released since 2005.

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Troubleshooting R Installations

Published 2016-06-16 by Kevin Feasel

Ginger Grant walks through how to fix a couple issues you might run into while installing SQL Server R Services:

If you look at the code from the interactive window, you will notice that the error occurred with trying to run rxSummary. In both cases I didn’t get the error when I changed the compute context to SQL Server from local, but when I tried to run a function which runs on the server. In both cases the R tools where installed prior to installing SQL Server 2016. The Open Source R tools install to C:\Program Files\R\R-3.3.0 (your version number may be higher). The Microsoft R Open installs to C:\Program Files\Microsoft\MRO\R-3.2.5. To use the libraries needed for the RevoScaleR libraries included in R Server, the version of Microsoft R required is Microsoft RRE, which is installed here C:\Program Files\Microsoft\MRO-for-RRE\8.0. Unfortunately, SQL Server 2016 shipped with version 8.0.3 not 8.0.0. If you are getting data and using a local compute context, you will have no problems. However, when you want to change your compute context to run on SQL Server, you will get an error.

While I received a different error on the server than my laptop, the reason for both messages was the same. Neither computer was running version 8.0.0.3 of the R client tools. On the server I was able to fix the error without downloading a thing. After installing a stand-alone version of R Server from the SQL Server Installation Center, the error went away and I got results when trying to run rxSummary. Unfortunately, it was not possible for me to run R Server on my laptop, as R Server is disabled from within the Installation Center. I believe that is because I have SQL Server 2016 developer edition on a laptop, not on a server. I needed to do something else to make it work.

Click the link for the full story.

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Direct Seeding Availability Group Replicas

Published 2016-06-16 by Kevin Feasel

Mike Fal is excited about direct seeding of Availability Groups in SQL Server 2016:

In SQL Server 2012 and 2014, creating an Availability Group could take a significant amount of work. One of the more tedious tasks is setting up your replica databases. This is because that you need to restore your database to your replica node in a state close enough to the primary to allow synchronization to happen. It can take several log backup restores to hit that magic window where you can join the database on the secondary node. Then, you get to do it again on the next replica!

Enter direct seeding in 2016. With this feature you no longer have to do any of the restores. You simply create your replicas with direct seeding enabled, then when you add a database to the AG, SQL Server will directly seed the database to your replica nodes. It’s surprisingly simple.

This sounds pretty interesting.

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Compressing LOB Data

Published 2016-06-16 by Kevin Feasel

Andy Mallon wants to compress LOB data:

The COMPRESS() function takes an input of string or binary data, and applies the gzip algorithm to it. It returns a value of type varbinary(max). In essence, instead of storing string or binary data, you can gzip it up and store it in a varbinary(max) column. There’s also a DECOMPRESS() function for when you are reading the data and need to unzip it.

This costs some CPU, but gzip can save quite a bit of space. How much space, and whether it’s worth the CPU cost will vary depending on your data and workload. In this blog post, we’ll take a look at one table. We’ll look at the space savings we get out of using COMPRESS(), and we’ll look at the effort necessary to implement it.

Read on for Andy’s test and thoughts.

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Plan Explorer Supports SSMS 2016

Published 2016-06-15 by Kevin Feasel

SQL Sentry Plan Explorer is now compatible with SQL Server 2016:

We’ve been busy modifying SQL Sentry Plan Explorer so it will work seamlessly with the changed add-in model in the new Management Studio. (As a bit of background, SSMS is now based on the Visual Studio 2015 shell, and some work is required to transition existing add-ins.)

I am happy to announce that, as of today, Plan Explorer 2.8 (build 10.1.94), with add-in support for SSMS 2016, is now available!

Huzzah.  That’s two plug-ins down and two more to go before I’m 100% ready for SSMS 2016.

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Primary And Foreign Keys

Published 2016-06-15 by Kevin Feasel

Shane O’Neill discusses primary key and foreign key constraints:

If you check the two definitions for Primary key and Foreign key you’ll see that, even though they are both called keys, they serve two different purposes; namely identifying rows and enforcing links.

And those two purposes are not mutually exclusive!

A column/column combo that identifies a row can also be used to enforce a link back to another table (or itself, as shown above with Foreign keys).

The assumption, that if you were one then you couldn’t be the other, was incorrect. If your business rules call for it, don’t let a column being one type of key stop it from being the other.

Not included but still important are unique constraints.

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Finding File Growth

Published 2016-06-15 by Kevin Feasel

Andy Galbraith shows how to use extended events to track file growth events:

…but what does this have to do with Extended Events?

As I started out, I was looking for something slick I do with a trace that I could replicate in Extended Events, and this was a great candidate.

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The catch as I discovered, is that while file growths are captured in the default trace, they are *not* in the system health session…

Fortunately, you can create your own XEvent and Andy gives us the details.

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Creating R Code

Published 2016-06-15 by Kevin Feasel

Ginger Grant introduces us to Microsoft R:

Microsoft has not one version of R, they have two but two. These two different versions are needed because they have two different purposes in mind. Microsoft R Open, is open source and fully R compatible and is faster than open source R because they rewrote a number of the algorithms to include multi-threaded math libraries. If you want to run R code on SQL Server, this is the not the version you want to use. You want to use the non-open source version designed to run on R Server, which is included with SQL Server 2016, Microsoft RRE Open. This version will run R code not only in memory but swap to disk, to create code which can access SQL Server data without needing to create a file, and can run code on the server from the client. The version of RRE Open which is included in SQL Server 2016 is 8.0.3.

She follows this up with a demo program to pull data from a SQL Server table and generate a histogram.  If you have zero R experience, there’s no time like the present to get started.

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Alerting On Drastic Changes

Published 2016-06-15 by Kevin Feasel

Rob Collie has a post on using Power BI to spot outliers:

The basic idea here is “alert me if something has changed dramatically.”  If there’s a corner of my business that has spiked or crashed in a big way, I want to know.  If something has dramatically improved in a particular region, I may want to dive into that and see if it’s something we can replicate elsewhere.  And if something has fallen off a cliff, well, I need to know that for obvious reasons too.  And both kinds of dramatic change, positive and negative, can easily be obscured by overall aggregate values (so in some sense this is a similar theme to “Sara Problem?”)

So the first inclination is to evaluate distance from average performance.  And maybe that would be fine with high-volume situations, but when we’re subdividing our business into hundreds or perhaps thousands of micro-segments, we end up looking at smaller and smaller sample sizes, and “normal” variation can be legitimately more random than we expect.

This looks really cool.  If you read the comments, Rob notes that performance does break down at some point.  If you start hitting that point, I’d think about shifting this to R.

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Implementing SoundEx

Published 2016-06-15 by Kevin Feasel

Dror Helper shows how to implement SoundEx in C#:

It’s fairly easy to follow the steps of the algorithm (as defined by Wikipedia):

  1. Retain the first letter of the name and drop all other occurrences of a, e, I, o, u, y, h, w.

  2. Replace consonants with digits as follows (after the first letter):

    • b, f, p, v → 1

    • c, g, j, k, q, s, x, z → 2

    • d, t → 3

    • l → 4

    • m, n → 5

    • r → 6

  3. If two or more letters with the same number are adjacent in the original name (before step 1), only retain the first letter; also two letters with the same number separated by ‘h’ or ‘w’ are coded as a single number, whereas such letters separated by a vowel are coded twice. This rule also applies to the first letter.

  4. If you have too few letters in your word that you can’t assign three numbers, append with zeros until there are three numbers. If you have more than 3 letters, just retain the first 3 numbers.

SQL Server also supports SOUNDEX as a built-in function.

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