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Month: January 2017

Polybase And Azure SQL Data Warehouse

Published 2017-01-05 by Kevin Feasel

I have a post on using Polybase with Azure SQL Data Warehouse:

That’s a header row, and I’m okay with it not making its way in.  As a quick aside, I should note that I picked tailnum as my distribution key.  The airplane’s tail number is unique to that craft, so there absolutely will be more than 60 distinct values, and as I recall, this data set didn’t have too many NULL values.  After loading the 2008 data, I loaded all years’ data the same way, except selecting from dbo.Flights instead of Flights2008.

Click through for more details, including the CETAS statement, which I’d love to see in on-prem SQL Server.

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Filtered Indexes And Parameters

Published 2017-01-05 by Kevin Feasel

Erik Darling shows an example of what happens when you have a filtered index and parameterize the filter:

It Is Known

That when you use filtered indexes, they get ignored when your queries are parameterized. This is a Plan Caching Thing©, of course. The simplest example is a bit column with a filtered index. If your index is on WHERE Bit = 1, it doesn’t have data for WHERE Bit = 0. That index would only be suitable for one variation of the query, so caching a plan that uses an index which can’t be reused for every variation isn’t feasible.

Read on for a couple examples, and check the comments on this as well.

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Using RTVS

Published 2017-01-05 by Kevin Feasel

David Eldersveld gives three reasons why you might be interested in R Tools for Visual Studio:

2. Incorporate R projects as part of a broader Visual Studio solution
Many Visual Studio solutions end up being a collection of individual projects. More often than not, these projects are logically joined by virtue of being part of the same business solution, but each one can incorporate different components or languages. For example, you may architect a solution that involves separate projects for loading data­­ with Azure Data Factory, analysis with R, a front-end C# web app, etc. Rather than keep your R code siloed off in a separate solution, unite it with the rest of your code for development and source control.

This is my primary reason.  R Studio is still my go-to option, but RTVS is maturing fairly nicely.  It still feels slower than R Studio when displaying data on-screen (especially when you’re spitting out a couple hundred lines of text), but that Visual Studio integration will go far.  A fourth reason that David does not mention:  it generates the really ugly sp_execute_external_script code for SQL Server R Services.

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Figuring Out Work-Life Balance

Published 2017-01-05 by Kevin Feasel

Sander Stad talks work-life balance:

The thing that comes up when I read this is that in most situations it will not work because you’re removing all the flexibility. The other thing is that most companies evaluate employees based on their availability and their flexibility.

There also a side note that employers are allowed to make different arrangements with employees.
Employers will probably adjust contracts from this point on that, if you’re in some sort of position where the availability is important, you’re obliged to answer which will render the law useless in a lot of situations.

There’s no one answer here, but it’s an important topic to think about.

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Memory-Optimized Tables In Query Store

Published 2017-01-05 by Kevin Feasel

Enrico van de Laar looks at how Query Store treats memory-optimized tables and natively compiled stored procedures:

Interestingly enough, no runtime statistics are returned for our natively stored procedure. As it turns out, we need to specifically enable the collection of statistics for natively compiled stored procedures through the sp_xtp_control_query_exec_stats stored procedure. Keep in mind, though, that enabling the collection of statistics for natively-compiled stored procedure can cause performance degradation. Thankfully we can very easily control the collection of statistics by enabling it for only specific natively compiled stored procedures and turn it on and off directly.

Read the whole thing.  Long story short:  they work together nicely.

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Elastic Pool Database Sizes

Published 2017-01-05 by Kevin Feasel

Vincent-Philippe Lauzon looks at how you can size databases with an Azure Elastic Pool:

We can’t change a database maximum size in the portal (as of December 2016).

Using ARM template, it is easy to change the parameter.  Here, let’s simply show how we would change it for an existing database.

Building on the example we gave in a previous article, we can easily grab the Pool-A-Db0 database in resource group DBs and server pooldemoserver:

Click through for all the details.  I highlighted this snippet as another point that the most important language for a Windows administrator to learn nowadays is Powershell.

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Clustering SQL Server On Linux

Published 2017-01-05 by Kevin Feasel

Joey D’Antoni has some notes on clustering a SQL Server instance running on Linux.  First, some quick notes:

One other thing that wasn’t in BOL, that I had to troubleshoot my way through is that just like a cluster on Windows, you have a cluster identifier and floating IP address. I had to add that to /etc/hosts on each of my nodes to get it to resolve. The article mentions turning off fencing for non-prod environments—I had to do that in order to get failover working correctly in my environment.

Then some more notes:

It was faster than building a Windows cluster

It took me a while, I laughed, I cried, I cursed a lot, but if I look at the time it took for me to actually build the cluster and install SQL Server, it was a much faster process. Much of this comes down to the efficiency of the SQL Server installation process on Linux, which is as simple as running yum install mssql-server (mostly). Which leads me to my next point..

As Joey notes, SQL Server clustering on Linux is in its infancy.  It’s nice that it works right now, but expect improvements over the next version or two.

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Visual Studio Code

Published 2017-01-05 by Kevin Feasel

Rob Sewell shows how to run SQL Server queries using Visual Studio Code:

Reading this blog post by Shawn Melton Introduction of Visual Studio Code for DBAs reminded me that whilst I use Visual Studio Code (which I shall refer to as Code form here on) for writing PowerShell and Markdown and love how easily it interacts with Githuib I hadn’t tried T-SQL. If you are new to Code (or if you are not) go and read Shawns blog post but here are the steps I took to running T-SQL code using Code

I played around with an early version of this and my thought was that there were some nice improvements over Management Studio (like being able to filter and sort the result set grid without going back to the server), but that there are still too many nice things Management Studio does for me to take a serious look at it.  Still, I’m hopeful that Microsoft moves in the direction of having a fully-featured querying tool for Linux so I can finally join the perpetual Year of the Linux Desktop.

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Why Care About The Data?

Published 2017-01-04 by Kevin Feasel

Rob Collie explains some of the benefits of Power BI with respect to its ability to dig into data problems:

Many problems/opportunities can ONLY be addressed by making thousands of small behavior changes, on an ongoing basis, out in the “trenches.”  In other words, there are some which CANNOT be addressed by a small number of smart decisions made at the top of the org.  Improved pricing behavior by the sales force for instance.  Improved quality of service by field technicians, for another.

How do you make that happen?  How do you influence a large number of people to behave differently on an ongoing basis, especially when they operate at a distance (both organizationally and physically) from you?

Fancy management consulting firms charge six-seven figures to do this, but with Power BI and/or Power Pivot, it’s no longer necessary to make that outlay.  We’ve seen organizations crack this nut with in-house resources, modest budgets, and short timelines – even though the impact is absolutely enterprise-wide.  It takes some thought and iteration, for sure, but primarily, you “just” need to build a good scorecard.

This is a non-technical post, but I like it a lot because it helps motivate decisions and gives you a good reason to investigate whether your tools are doing the work you need them to do.

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Batches And Stored Procedure Creation

Published 2017-01-04 by Kevin Feasel

Steve Jones has a warning for when you create a stored procedure:

Why is my select code in there? That was designed to be a piece of test code. Shouldn’t the BEGIN..END after the AS define my procedure?

Actually it doesn’t. the procedure doesn’t end until the CREATE PROCEDURE statement is terminated. That termination comes by ending the batch. The CREATE PROCEDURE documentation has this limitation:

The CREATE PROCEDURE statement cannot be combined with other Transact-SQL statements in a single batch.

This means that anything else you have in that batch will be considered as part of the procedure, regardless of BEGIN..END.

Judicious usage of the GO statement can help keep you out of trouble.

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