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Day: July 22, 2019

Comparing Classification Model Quality

Stephanie Glen looks at ways to compare model evaluation for classification models:

In part 1, I compared a few model evaluation techniques that fall under the umbrella of ‘general statistical tools and tests’. Here in Part 2 I compare three of the more popular model evaluation techniques for classification and clustering: confusion matrix, gain and lift chart, and ROC curve. The main difference between the three techniques is that each focuses on a different type of result:

– Confusion matrix: false positives, false negatives, true positives and true negatives.
– Gain and lift: focus is on true positives.
– ROC curve: focus on true positives vs. false positives.

These are good tools for evaluation and Stephanie does a good job explaining each.

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Databricks Runtime 5.5

Bilal Aslam and Yifan Cao announce Databricks Runtime 5.5:

Secrets API in R notebooks
The Databricks Secrets API [Azure|AWS] lets you inject secrets into notebooks without hardcoding them. As of Databricks Runtime 5.5, this API is available in R notebooks in addition to existing support for Python and Scala notebooks. You can use the dbutils.secrets.get function to obtain secrets. Secrets are redacted before printing to a notebook cell.

There are some good updates in this release. Read on for the full list.

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Multi-Server Patching with dbatools

Eric Cobb shows how you can use dbatools to upgrade multiple SQL Server instances:

Patching SQL Server can sometimes be a time consuming process, especially when you have multiple servers that need to be patched. Remoting in to each box to run through the update wizard is tedious, and if you have multiple patches to apply you’re going to be spending a considerable chunk of time on it.

Thankfully, the dbatool Powershell Module makes this process much easier! In fact, once you get it figured out, using Update-DbaInstance to patch your SQL Servers becomes very simple. But, getting it figured out can be a little confusing, so I’ve outlined the steps below that I use. The biggest hangups I had were setting up a central patching location and using a credential to access it.

Click through to see an example of this in action.

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Diagnosing Analysis Services with SSASDiag

Chris Webb discusses SSASDiag:

There are a lot of great community-developed tools out there for Analysis Services developers to use (BI Developer ExtensionsDAX StudioTabular EditorAnalysis Services Query Analyzer to name a few) and they have saved me vast amounts of time and effort over the years. When I joined Microsoft last month I came across one which I had never seen before but which is nevertheless quite mature and feature-rich: the SSAS Diagnostics Tool or SSASDiag for short. It’s available on GitHub here:

Read on for Chris’s initial thoughts and check out the tool.

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SQL Server 2017 and Visual Studio 2017/2019 Installation Error

Hamish Watson walks us through an error which happens when you install SQL Server 2017 and Visual Studio 2019 in the “wrong” order:

This blog post is about a situation that initially perplexed me – I was installing SQL Server 2017 onto a new DEMO machine – running Windows Server 2019. This install is one I have done over 50 times, if not more.

Halfway through I got an interesting error that (1) I’ve never seen before and (2) did not expect post SQL Server 2014.

MSI Error: 1706 An installation package for the product Microsoft SQL Server 2012 Native Client cannot be found. Try the installation again using a valid copy of the installation package ‘sqlncli.msi’.

Read on for the solution. And note that it also happens with Visual Studio 2017.

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Finding Broken Code in SQL Server

Pamela Mooney shows us how we can find broken code on our SQL Server instances:

Before we approached our last major SQL Server upgrade, I was curious about what might break.  Yes, I had used the DEA to check our code against deprecated or discontinued code.  But I am talking about code that might not have been used in some time and would break because objects no longer existed, or other things like that.  So I wrote these scripts to refresh the sprocs, views and functions in our (non-production) environment.

Pamela’s motivation was to handle code which breaks during an update. You can also use this to see what you can probably deprecate—if the view doesn’t work, it can’t be in use. That means either someone should fix it or drop it.

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Shortest Path with T-SQL Graph

Niko Neugebauer shows us how to use the SHORTEST_PATH() function with graph tables in SQL Server 2019:

SHORTEST_PATH() function will allow you to traverse the given graph looking for the shortest path between different Nodes. It will use the Arbitrary Length Pattern to define the traversal path. This function will not return any results any results in SELECT clause because it must be used within MATCH clause only!

To my understanding because one of the mechanisms being used is depth-first search, in situation where multiple shortest path do exist, the function will return the first one only.

Click through for a detailed article on the topic. There are some nice parts to this but also a couple not-so-nice limitations in the current CTP.

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