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Day: April 9, 2025

The Basics of Bayes’ Theorem

Published 2025-04-09 by Kevin Feasel

I have a new video:

In this video, I provide an introduction to Bayes’ theorem, explaining the key concepts and terms, as well as solving a totally realistic problem via Bayesian analysis.

My goal in this video was to explain a counter-intuitive phenomenon: how much a positive test or piece of information moves the needle depends primarily on how frequently the event normally happens and how frequently we generate false positives in tests. The less common the scenario, the less your positive test actually moves the needle.

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Error Handling in Powershell

Published 2025-04-09 by Kevin Feasel

Patrick Gruenauer catches ’em all:

Error handling is a critical aspect of writing robust scripts in any programming language. PowerShell provides a powerful structure for handling errors gracefully using try, catch, and finally blocks. These constructs allows us to manage exceptions and ensure that important cleanup actions are performed, even when errors occur. In this blog post, I will show you how to use try catch finally in PowerShell. Let’s jump in.

Click through to see how the logic works in Powershell, as well as how you can read the exception itself in the catch block.

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Finding Tables Matching a Pattern via dbatools

Published 2025-04-09 by Kevin Feasel

Jess Pomfret looks for old tables:

There are many reasons why you might end up with tables named something_old in your database. Perhaps this is part of your decommission strategy, to rename them to make sure they really aren’t in use. Or, it could be because you need to make schema changes, you can rename the current table and create a new table with the desired schema. But, the key to this blog post is when you then forget to come back and clean these tables up. We can easily find them with a dbatools command.

Read on to see how you can use dbatools cmdlets to find and remove these deprecated tables.

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Transmitting Printed Data in Notebooks

Published 2025-04-09 by Kevin Feasel

Marc Lelijveld provides a public service announcement:

When working with Notebooks in Microsoft Fabric, exporting and reusing them across environments or tenants might seem like a harmless, even convenient, task. Whether you’re sharing a template with a colleague, moving assets between workspaces, or contributing to the community — the last thing you’d expect is to accidentally include data along with your code.

But that’s exactly what can happen.

For people who have worked with Jupyter notebooks in the past, this is a fairly obvious result. But if you aren’t familiar with the platform, that idea may seem weird. Marc does provide some options for exporting notebook contents, and you can also clear the cell contents before exporting.

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SELECT FOR UPDATE in PostgreSQL

Published 2025-04-09 by Kevin Feasel

Umair Shahid preps for an update:

When multiple transactions need to modify the same rows, ensuring data consistency can become tricky. A single wrong approach to locking can lead to suboptimal performance or even bring your application to a standstill as numerous transactions block one another. One tool in PostgreSQL’s arsenal to handle concurrency is SELECT FOR UPDATE. It allows you to lock specific rows before updating them, preventing other transactions from modifying those rows until your transaction completes.

In this blog, we will dive deep into SELECT FOR UPDATE in PostgreSQL. We will explore how it helps in reducing contention, avoiding deadlocks, and ultimately boosting performance when dealing with highly concurrent applications.

Click through to understand how this works and also some notes on when to use it and when not to use it.

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