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Author: Kevin Feasel

Altering User-Defined Table Types

Published 2020-10-20 by Kevin Feasel

Michael J. Swart has a clever solution to the inability to alter user-defined table types:

Last year, Aaron Bertrand tackled the question, How To Alter User Defined Table Types. Aaron points out that “There is no ALTER TYPE, and you can’t drop and re-create a type that is in use”. Aaron’s suggestion was to create a new type and then update all procedure to use the new type.

I think I’ve got a bit of improvement based on sp_rename and sp_refreshmodule. 

This is a clever solution. Prior to it, my workflow was:

  1. Create a new user-defined table type
  2. Create new stored procedures which reference the new user-defined table type
  3. Alter and deploy code to call these new stored procedures
  4. Drop the old procedure and user-defined table type

If the changes are such that they don’t require immediate app changes to use (for example, adding a nullable column to the UDTT), this can save a lot of effort.

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Power BI Custom Format Strings

Published 2020-10-20 by Kevin Feasel

Matt Allington is back from the future:

The ability to apply custom format strings directly inside the Power BI Desktop report view was first announced back in February 2020. At the time I was quite excited and tweeted about it only to find out shortly thereafter that it hadn’t been released at all! It seems it was a release candidate that was pulled at the last minute, but no one updated the announcement! Then late last week I was doing some work in Power BI desktop and noticed that this feature has now been released and is working (I don’t recall seeing a new announcement at all).

Below I show you how to use custom formatting strings in Power BI.

Click through to see how it works, as well as a couple gotchas.

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Resolving Call Stack Symbols on SQL Server 2019

Published 2020-10-20 by Kevin Feasel

Paul Randal takes us through a change to SQL Server 2019:

After beating my head against the proverbial wall for an hour, I wondered if I had the wrong symbols somehow. I checked with the excellent SQLCallStackResolver tool from GitHub (authored by Arvind Shyamsundar from the Product Group) and that worked fine with the symbols I had, so it had to be something within SQL Server.

Read on to see the answer.

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Creating Power BI External Tools in VS Code

Published 2020-10-20 by Kevin Feasel

Phil Seamark takes us through creating external tools in Power BI:

For this article, I want to share a way for you to create your own Power BI “Helper Tool” and register it as an external tool in Power BI. This article carries on from some of my recent articles on how you can use Visual Studio Code to help automate specific tasks by taking advantage of the existing Analysis Services client libraries.

In my role, I often connect to AS models (Power BI or Azure AS) and often want to perform specific tasks quickly. The helper tool I share here allows you to connect easily to an AS model and then perform helpful tasks. I’ve deliberately kept the look and feel of the tool to be ‘old school’ like me. 

Click through for the step-by-step instructions.

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Access Violation Querying System Table Functions with Parallelism

Published 2020-10-20 by Kevin Feasel

Eitan Blumin has a write-up of an interesting bug in SQL Server:

The Access Violation error is triggered when an execution plan with parallelism involves specific system table functions. We found that the error occurs ONLY with parallel execution plans.

Therefore, in order to reproduce it, you’ll need:

– SQL Server instance with MaxDOP setting not equal to 1
– At least 2 available CPU cores

Click through for additional details, including a script to generate the same error yourself.

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The Main Components of Apache Spark

Published 2020-10-19 by Kevin Feasel

Manoj Pandey walks us through the key components in Apache Spark:

1. Spark Driver:

– The Driver program can run various operations in parallel on a Spark cluster.

– It is responsible to communicate with the Cluster Manager for allocation of resources for launching Spark Executors.

– And in parallel it instantiates SparkSession for the Spark Application.

– The Driver program splits the Spark Application into one or more Spark Jobs, and each Job is transformed into a DAG (Directed Acyclic Graph, aka Spark execution plan). Each DAG internally has various Stages based upon different operations to perform, and finally each Stage gets divided into multiple Tasks such that each Task maps to a single partition of data.

– Once the Cluster Manager allocates resources, the Driver program works directly with the Executors by assigning them Tasks.
 

Click through for additional elements and how they fit together.

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Optical Character Recognition with Tesseract and Databricks

Published 2020-10-19 by Kevin Feasel

Alex Aleksandrov takes a look at optical character recognition with the Tesseract library:

The topic of Optical Character Recognition (OCR) is not an unexplored field to the Adatis audience. Some Adati like Kalina Ivanova (link1, link2) and Francesco Sbrescia (link3) have already explored this topic from the perspective of Azure Cognitive Services and Azure Data Lake. In my first blog, I would like to explore this topic from a different perspective: using Tesseract and Databricks.

Click through for instructions.

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Changing Power BI Slicer Appearance

Published 2020-10-19 by Kevin Feasel

Prathy Kamasani has a video:

In my recent open data project, I created a single page report model with a sparse slicer. It’s a good trick for anyone who wants to make their slicer look a bit sleeker. Like any other visual in Power BI, Slicers also have many properties. By default, below is how slicer looks in Power BI, but I made few changes to make it look like the one on left, in a few steps.

Click through for the video.

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Parsing Parameter Default Values in Powershell

Published 2020-10-19 by Kevin Feasel

Aaron Bertrand continues a series:

In part 1 and part 2 of this series, I introduced ParamParser: a PowerShell module that helps parse parameter information – including default values – from stored procedures and user-defined functions, because SQL Server isn’t going to do it for us.

In the first few iterations of the code, I simply had a .ps1 file that allowed you to paste one or more module bodies into a hard-coded $procedure variable.

Read on to see what’s new in the ParamParser repo.

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Swart’s Ten Percent Rule: User Connections

Published 2020-10-19 by Kevin Feasel

Michael J. Swart applies Swart’s 10% Rule to maximum simultaneous user connections:

The maximum number of user connections that SQL Server can support is 32,767. That’s it. That’s the end of the line. You can buy faster I.O. or a server with more CPUs but you can’t buy more connections.

I actually mentioned this limit in the post where I introduced Swart’s 10% rule: “If you’re using over 10% of what SQL Server restricts you to, you’re doing it wrong” In that post, I was guarded about that statement as it applied to the user connection limit. But I’d like to upgrade that to elevated.

This is Threat Level Vermillion, people!

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