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Day: June 25, 2026

Snapshot Testing in R

Published 2026-06-25 by Kevin Feasel

Jakub Sobolewski drills into a particular form of testing:

Snapshot testing is not about screenshots.

Most people meet it through UI regression tests: render a component, save a picture, fail the build when the picture changes. So the technique gets filed away as “the thing that compares images.” That is one use. But not the only one.

The mechanic underneath is general. Capture some output, save it to a file, and on every later run compare fresh output against the saved copy. The output can be a plot. It can also be console text, a log, a data frame, an error message, or a deeply nested list. Anything you can serialize, you can snapshot.

Read on to see how you can perform snapshot testing, using examples in R to demonstrate. H/T R-Bloggers.

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Trusting Outputs from Fabric Data Agents

Published 2026-06-25 by Kevin Feasel

Jens Vestergaard says don’t trust, do verify:

In two previous posts I went down the path of getting a semantic model ready for AI: descriptions on every measure, an instructions file, the schema tidied up enough that a Fabric data agent has something real to read. That work has a satisfying endpoint. The model looks ready.

Ready is not the same as right.

The kind of evaluation Jens is talking about is fundamental to good business intelligence practices, regardless of whether you throw language models into the mix. Where language models do add complexity is the arbitrary scope of questions, how ambiguous people tend to be when writing, and the stochastic nature of answers. All of that makes the problem harder, though at least it isn’t an entirely different class of problem to solve.

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What’s Common in Regular Expressions

Published 2026-06-25 by Kevin Feasel

John Cook muses on regular expression libraries:

The most frustrating aspect of regular expressions is that implementations vary. Features supported in one tool may not be supported at all in another tool, or they may be supported with slightly different syntax.

I learned regular expressions in the context Perl, a maximalist regex environment. This led to frustration when features I expect to work are missing [1]. One way around this is to use Perl analogs of other tools, but this is very non-standard. I want to be able to send colleagues and clients code that works out of the box.

Click through for some thoughts about the lowest common denominator for what products tend to support around regex. This is one of several tricky things when working with regular expressions: you may know a great way to solve a specific class of problem, but does the particular engine you’re using actually support that method?

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An Introduction to Memory Grants in SQL Server

Published 2026-06-25 by Kevin Feasel

Erik Darling has a new video for us:

Erik monitoring tool mogul darling here with Darling Data. In today’s video, much like I think I foreshadowed in yesterday’s office hours video, we are going to talk about memory grants. We’re going to do a somewhat gentle introduction to them and then in the next video we’ll talk a little bit more about where they get interesting. 

Erik shares his perfectly reasonable take on the nature of strings. I’d probably also get rid of dates as well—too much confusion there for my taste.

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SQL Formatting in SSMS 22.7

Published 2026-06-25 by Kevin Feasel

Chad Callihan tries out a new feature:

Code formatting can be a touchy subject. Sometimes there are clear rules to designate right and wrong, and sometimes there’s not. Tabs versus spaces, anyone?

Surprisingly, SQL Server Management Studio has never had a built-in SQL formatter. Users were always left to use third-party tools or format by hand. But with the latest SSMS 22.7, SQL formatting finally comes built-in.

Let’s look at some examples and see how it performs.

Chad also spotted a problem in the formatter as it is in that release.

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