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Day: September 26, 2025

Testing in R with testthat

Published 2025-09-26 by Kevin Feasel

Aida Gjoka writes a test:

Testing is an important step when developing code in R or any other language. If you are a Python user, you can consider reading our previous blogs in pytest. Writing tests helps us make sure that the code is working as expected. In the R ecosystem, the testthat package is one of the most used frameworks. In this blog we will explore some of the main properties of {testthat} highlighting some of the most useful functions with some examples.

Read on to see how it works. This isn’t a mocking library, but rather an assertions-based testing library. And near the end, Aida includes an extra library that helps with plot testing.

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Code Blocks and Inline Code in Markdown

Published 2025-09-26 by Kevin Feasel

Mike Robbins continues a series on Markdown:

Technical writers often need to embed code in their articles, whether snippets, configurations, commands, or examples. When presented clearly, code in your articles reinforces understanding and helps readers follow along more easily. When presented poorly, it creates confusion and frustration. This article demonstrates how to use inline code and code blocks effectively in Markdown, ensuring your code is readable, maintainable, and helpful to your audience.

This is, fortunately, a bit of Markdown that is very consistent across platforms.

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Memory Grant Feedback Woes

Published 2025-09-26 by Kevin Feasel

Rebecca Lewis explains an issue with memory grant feedback in SQL Server:

Before SQL Server runs a query, it estimates how much memory it needs for sorting and joining. But what if it gets it wrong?

  • Too little memory → Spills to tempdb (slow)
  • Too much memory → Starves other queries

SQL Server 2017+ tries to fix bad estimates based on previous calls with ‘Memory Grant Feedback’.  Kinda like:  ‘Last time I gave you 2GB but you only used 50MB. Next time I’m giving you less.’

This is great in theory, though Rebecca shows a case in which the end result might not be great.

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SLRUs and MultiXacts in Postgres

Published 2025-09-26 by Kevin Feasel

Andrew Atkinson digs in:

The main purpose of SLRUs is to track metadata about Postgres transactions.

SLRUs are a general mechanism used by multiple types. Like a lot of things in Postgres, the SLRU system is extensible which means extensions can create new types.

The “least recently used” aspect might be recognizable from cache systems. LRU refers to how the oldest items are evicted from the cache when it’s full, and newer items take their place. This is because the cache has a fixed amount of space (measured in 8KB pages) and thus can only store a fixed amount of items.

Read on to learn more about these two concepts and how things have changed in Postgres 17.

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Viewing Security Settings in OneLake Catalog

Published 2025-09-26 by Kevin Feasel

Aaron Merrill announces a new preview feature:

Introducing the Secure tab in the OneLake catalog—your central place to understand and manage access across Fabric items. From a single view, you can workspace roles with the View users experience and inspect or modify role OneLake security roles with View security roles. The Secure tab brings a streamlined view for governance teams and workspace owners to quickly validate permissions and tighten least‑privilege access.

Click through to see how it looks.

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