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Day: August 5, 2025

Updates to Extensions in C# 14

Published 2025-08-05 by Kevin Feasel

The word miners in the NDepend blogging mines clue us in on an update to the C# language:

A few remarks:

  • If the extension is generic, the type parameter (if any) is specified immediately after the extension keyword.
  • The receiver ReadOnlySpan<T> span applies to one or more extension methods (or members) declared within the same extension block. This logical grouping is a core advantage of the new syntax, improving clarity and structure when extending a type.
  • As far as the C# compiler is concerned, the two methods Truncate() are strictly equivalent. Therefore, one must be commented out for the program to compile.
  • Notice the call to AsSpan() in the first line. Extension methods require the receiver type to match exactly ReadOnlySpan<T>, hence it doesn’t apply to string unless you explicitly cast. This is not specific to the new syntax but worth mentioning.

Read on for examples of how extension methods and extension members will open up opportunities to improve existing C# code.

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Reasons Regression Models Under-Perform

Published 2025-08-05 by Kevin Feasel

Ivan Palomares Carrascosa has a list:

In regression models, failure occurs when the model produces inaccurate predictions — that is, when error metrics like MAE or RMSE are high — or when the model, once deployed, fails to generalize well to new data that differs from the examples it was trained or tested on. While model failure typically shows up in one or both of these forms, the root causes can be more diverse and subtle.

This article explores some common reasons why regression models may underperform and outlines how to detect these issues. It is also accompanied by practical code excerpts using XGBoost — a robust and highly tunable ensemble-based regression model. Despite its popularity and power, XGBoost can also fail if not trained or evaluated properly!

These are high-level reasons but they’re good to keep in mind.

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Using a Child Pipeline Variable in a Parent Pipeline in Fabric Data Factory

Published 2025-08-05 by Kevin Feasel

Justin Bird passes back some information:

I answered a question on the Fabric community on return variables recently and thought I would expand upon it in a blog post. The question was how to use a variable derived in a child pipeline downstream in the parent pipeline. The person was specifically deriving a json object and wanted to iterate on the values in the parent pipeline.

Click through for the solution.

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Regular Expression-Based String Splitting in SQL Server 2025

Published 2025-08-05 by Kevin Feasel

Aaron Bertrand splits a string:

SQL Server users have been asking for native regular expression support for over two decades. There are third-party Common Language Runtime (CLR) modules that offer this functionality, but these can be complicated to install and simply aren’t possible in some environments. I want to split a string using a regular expression instead of a static string. Will that be possible in SQL Server 2025, without CLR?

Must not rant about CLR. Must not rant about CLR. Must not rant about CLR. (By the way, if you ever catch me in person, get me going about how CLR got the short end of the stick and how the ‘modern’ forms of the Common Language Runtime in SQL Server are not great.)

Aaron tries out a function built into SQL Server that allows you to split strings into result sets using a regular expression to perform the splitting, and shows off some of the more complicated scenarios that this can solve over a normal STRING_SPLIT() function call.

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Performance Optimizing PostgreSQL for RTABench Q0

Published 2025-08-05 by Kevin Feasel

Andrei Lepikhov gets under the hood:

I wanted to explore whether Postgres could be improved by thoroughly utilising all available tools, and for this, I chose the RTABench benchmark. RTABench is a relatively recent benchmark that is described as being close to real-world scenarios and highly selective. One of its advantages is that the queries include expressions involving the JSONB type, which can be challenging to process. Additionally, the Postgres results on RTABench have not been awe-inspiring.

Ultimately, I decided to review all of the benchmark queries, and fortunately, there aren’t many, to identify possible optimisations. However, already on the zero query, there were enough nuances that it was worth taking it out into a separate discussion.

Click through for a dive into this particular query and what Andrei did and some of the lessons you can draw from it.

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No More TLS 1.1 in Microsoft Fabric

Published 2025-08-05 by Kevin Feasel

Nisha Sridhar makes an announcement:

We have officially ended the support for TLS 1.1 and earlier on the Fabric platform. As previously announced, starting July 31, 2025, all outbound connections from Fabric to customer data sources must use TLS 1.2 or later.

This update follows our earlier announcement in the TLS Deprecation for Fabric blog, where we outlined the rationale and timeline for this transition.

Read on to see what you might need to do to keep up to date.

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