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Day: April 19, 2019

Forensic Accounting: Cohort Analysis

Published 2019-04-19 by Kevin Feasel

I continue my series on forensic accounting techniques with cohort analysis:

In the last post, we focused on high-level aggregates to gain a basic understanding of our data. We saw some suspicious results but couldn’t say much more than “This looks weird” due to our level of aggregation. In this post, I want to dig into data at a lower level of detail. My working conception is the cohort, a broad-based comparison of data sliced by some business-relevant or analysis-relevant component.

Those familiar with Kimball-style data warehousing already understand where I’m going with this. In the basic analysis, we essentially look at fact data with a little bit of disaggregation, such as looking at data by year. In this analysis, we introduce dimensions (sort of) and slice our data by dimensions.

Click through for some fraud-finding fun.

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Backing Up Database to Azure Blob Storage

Published 2019-04-19 by Kevin Feasel

Jamie Wick shows us how we can back up database directly to Azure Blob Storage:

Azure storage, as a backup destination for SQL backups, is a great option for organizations that are contemplating replacing older on-prem NAS appliances or improve their Disaster Recovery functionality. The tiered storage pricing, along with local and global redundancy options, can be much more cost-effective than many traditional backup options.

In this post, we’re going to look at some of the key concepts and restrictions, along with how to back up an SQL database to an Azure storage location.

Click through for the demo.

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Qualitative Analysis with Dendograms

Published 2019-04-19 by Kevin Feasel

Stephanie Evergreen explains what denodgrams are and when they can be useful visuals:

Dendrograms are not THE most common qualitative visual because they require a data generated through a hierarchical cluster analysis. Cluster analysis can be a useful tool in analyzing qualitative data. By clustering groups of participants with similar qualitative codes, you can better understand your findings. According to Henry & team, this analysis can help “reveal things like participant motive and the reasons behind counterintuitive findings.”

Check out Henry’s article to learn more about the analysis. Here, let’s just focus on describing a dendrogram that could display those hierarchical cluster analysis findings. They can be a little confusing at first, especially since the x-axis has 100% closest to the y-axis when we aren’t used to seeing it that way. Walk through this example with us.

Click through for an example. If it’s confusing at first, read to the end, as I think the concrete example helps everything click.

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Errors Updating Stats on Columnstore Indexes

Published 2019-04-19 by Kevin Feasel

Max Vernon walks us through some problems trying to update statistics on columnstore indexes:

The first error above would be seen if you have a SQL Server Agent job that updates statistics. The second error is how it looks in an SSMS Query window.

The error message claims that UPDATE STATISTICS can only be used on a columnstore index with the STATS_STREAM option. However, the Microsoft Docs UPDATE STATISTICS shows very “thin” documentation for the option, showing only these two tidbits:

<update_stats_stream_option>
Identified for informational purposes only. Not supported. Future compatibility is not guaranteed.

Columnstore indexes really don’t want their stats updated, apparently, and will fight you tooth and nail to prevent it.

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Long Weekend Learning Items

Published 2019-04-19 by Kevin Feasel

Kevin Chant has a few things you should check out if you’ve got several days of downtime:

Install and learn Docker
You can take the time over the Easter weekend to download and install Docker to see how you can use it. In addition, there are multiple posts online by people online that you can use as a starting point.
However, to start with you can read how to download and install it in detail here.

There are some good things on this list. Even if you don’t have a long weekend ahead of you, pick up some of these items gradually.

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Quick Thoughts on Dot-Sourcing in Powershell Modules

Published 2019-04-19 by Kevin Feasel

Cody Konior wants to speed up module loading:

One of the more heated ideas is that you should combine all of your scripts into a massive file and execute it once instead. Currently dbatools uses a mix of these techniques in great detail and to great success.

I don’t want to use a single file because I don’t like build the idea of a pre-compile build pipeline for a scripting language, so here’s an alternative and benchmarks of how these techniques stack up (taken on Windows 10 PS 5.1 obviously your results may differ).

Check out Cody’s example.

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Downgrading a SQL Server Database

Published 2019-04-19 by Kevin Feasel

Dave Mason goes against the flow:

One of the recurring questions I see on Stack Overflow is “How do I restore a SQL Server backup to a previous version of SQL Server?” The answer, of course, is you don’t. Upgrading a database to a newer (major) version is a one-way ticket–at least as far as the database files and subsequent backups go. I recently found myself in a similar position as all those hapless Stack Overflow questioners. I had a customer that had migrated to a newer version of SQL and they wanted to roll back to the previous version. What to do?

A couple of thoughts immediately came to mind. There’s the SQL Server Import and Export Wizard and the Generate and Publish Scripts Wizard. Neither of these sounded convenient. In particular, generating a script with both schema and 500 GB of data sounded like a fruitless endeavor. Two other options sounded much more appealing. So I focused on those.

Dave has a couple of creative methods effectively to downgrade a database.

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