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Curated SQL Posts

Reviewing Blocking and Deadlocking

Published 2026-04-10 by Kevin Feasel

Erik Darling digs into more functionality in his performance monitoring tool:

In this video, I delve into the blocking and deadlock monitoring capabilities of FreeSQL Server Performance Monitoring, a tool I’ve developed and made available on GitHub. With a focus on practicality and ease-of-use, I explain how we leverage extended events for both blocking and deadlock scenarios, ensuring that you can identify and address performance issues efficiently. Whether you’re using system health or prefer to rely on the block process report, my monitoring tool streamlines the process by automatically setting up necessary configurations and providing easy-to-understand visualizations of your SQL Server’s performance trends over time.

Click through for the video and transcript.

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Defining a Data Contract

Published 2026-04-10 by Kevin Feasel

Buck Woody becomes accountable:

A businessperson pulls a report from a data warehouse, runs the same query they’ve used for two years, and gets a number that doesn’t match what the finance team presented at yesterday’s board meeting. Nobody changed the report. Nobody changed the dashboard. But somewhere upstream, an engineering team renamed a field, shifted a column type, or quietly altered the logic in a pipeline, and nobody thought to mention it because there was no mechanism to mention it.

While we think of this as an engineering failure, it’s more of an implied contract failure. More precisely, it’s the absence of a formal contract. Data contracts are one of the most practical tools a data organization can adopt, and one of the most underused. The idea is not complicated: a data contract is a formal, enforceable agreement between the team that produces data and the team that consumes it. It defines what the data looks like, what quality standards it must meet, who owns it, and what happens when something changes. Think of it as the API layer for your data, the same guarantee a software engineer expects from a well-documented endpoint, applied to the datasets and pipelines your business depends on. This post is about why that matters at the CDO level and how to get them put in place.

Click through to learn more about what data contracts are and why they are useful. This post stays at the architectural level rather than the practitioner level, but lays out why it’s important to think about these sorts of things.

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Mirroring SQL Server 2025 to Microsoft Fabric

Published 2026-04-10 by Kevin Feasel

Reitse Eskens digs in:

Maybe you’ve read my blog post in the DP-700 certification series about mirroring data. You can find that one here. This blog will be longer and more technical. And involve SQL Server. To make reading a little easier, I’ve listed the Microsoft Learn pages at the end of this blog post.

While writing the DP-700 post, I realised I wanted to dig a little deeper. Not only because I’m presenting a session on this subject, but also to learn more about the processes behind it. And, there’s SQL Server involved, something I still have a soft spot for in my heart. Or maybe even more than that.

The fact that your SQL Server instance has to be Arc-enabled is a bit annoying.

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Updates to Fabric Eventstream

Published 2026-04-10 by Kevin Feasel

Alicia Li and Arindam Chatterjee share some updates:

Over the first quarter of 2026, Fabric Eventstreams shipped meaningful improvements across three themes that have repeatedly come up in feedback from our broad community of customers and partners: broader connectivity, richer real-time processing, and secure enterprise‑ready networking and operations.

This post highlights some of the most impactful new Eventstreams-related features and capabilities delivered between January and March 2026.

Click through to see what’s new. Some of this is GA, though a good amount is in preview.

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Comparing Schemas between PostgreSQL and Oracle

Published 2026-04-09 by Kevin Feasel

Laurenz Albe makes a comparison:

Recently, somebody asked me for a reference to a blog or other resource that describes how schemas work differently in Oracle. I didn’t have such a reference, so I’m writing this article. But rather than just describing Oracle schemas to a reader who knows PostgreSQL, I’ll try to present the topic in a way that helps Oracle users understand schemas in PostgreSQL as well. Since I already wrote about the difference between database transactions in Oracle and PostgreSQL, perhaps this can turn into a series!

Click through for the comparison. As far as SQL Server, here’s my off-the-cuff take:

  • Users and schemas — SQL Server follows the same model PostgreSQL does.
  • Schemas as namespaces — SQL Server follows roughly the same model Oracle does.
  • Schemas and object ownership — Different from the two, based on my reading. Objects are owned by the security principal that owns the schema. This is closer to the Oracle model but isn’t quite the same.
  • Schemas and privileges –Because of how object ownership works, there’s more flexibility to the SQL Server model, but also more complexity. In practice, it’s closer to the way PostgreSQL works.
  • Default schema — Different from the two. With one-part naming, SQL Server will first try the user’s default schema. If the object is not there, it checks dbo. That check, by the way, takes a small amount of time but can add up if you’re talking hundreds of thousands of transactions per second. Just ensuring you have consistent two-part naming can be a marked performance improvement on extremely busy servers.
  • System schemas — The sys schema includes system tables and Dynamic Management Views, and INFORMATION_SCHEMA provides the types of information the ANSI SQL standard requires.
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The Death of SQL Server, Yet Again

Published 2026-04-09 by Kevin Feasel

Rebecca Lewis states that rumors of SQL Server’s demise have been greatly exaggerated:

LinkedIn is doing that thing again. ‘Is SQL Server Dead?’ posts are getting traction, the comment sections are lit, and I’m sure a lot of managers out there are forwarding one of them to a DBA with a question mark and no context. It happens every few years. NoSQL was going to kill it. The cloud was going to kill it. Now it’s AI and Fabric. I’ve been doing this for 28 years. Let me save you some time.

No. SQL Server is not dead or even dying. But something is changing — and we need to understand what.

Read on for Rebecca’s take. At the very least, I strongly agree with the general thrust of her argument. And, of course, I would be remiss if I didn’t mention Feasel’s Law here.

What makes this tricky is that there’s definitely more impetus from Microsoft to get people in Azure and using SQL Server-derived products up there. And the stability of the product has definitely taken a hit in the past couple of versions, something I chalk up to the organization removing QA teams back in about 2018. I do think the biggest competition for SQL Server is open-source relational databases, particularly PostgreSQL. At the same time, it’s not just a matter of “Let’s take a weekend and replace database management systems.” For that reason (among others), I do expect to see SQL Server around for quite a while.

And do check out Andy Yun’s comment. It links to a paper I’ve had on my to-read list that a Shop Talk viewer gave me while I was ranting on a somewhat similar topic.

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pg_prewarm and a Bug in PostgreSQL 16.8

Published 2026-04-09 by Kevin Feasel

Warda Bibi explains an issue:

Recently, we encountered a production incident where PostgreSQL 16.8 became unstable, preventing the application from establishing database connections. The same behavior was independently reproduced in a separate test environment, ruling out infrastructure and configuration issues. Further investigation identified the pg_prewarm extension as the source of the problem.

This blog post breaks down the failure, the underlying constraint, why it manifests only under specific configurations, and the corresponding short-term mitigation and long-term fix.

Click through for those details. The bug is no longer an issue as of PostgreSQL 16.10.

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Performing a GROUPBY in Excel

Published 2026-04-09 by Kevin Feasel

Ben Richardson explains a DAX function:

If you’ve ever built a summary table in Excel by writing five separate SUMIFS formulas – one for each region, product, or department – you’ll appreciate what GROUPBY does.

It collapses all of that into a single formula that updates automatically, sorts itself, and can even filter out rows you don’t care about.

Introduced to Microsoft 365 in late 2024, GROUPBY is one of the most practically useful additions Excel has had in years.

But it also comes with real limitations that most people gloss over.

Read on to learn more about the capability and one big catch.

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Optional SUBSTRING() Length in SQL Server 2025

Published 2026-04-09 by Kevin Feasel

Louis Davidson points out a neat update:

Sometimes along comes a feature that seems so obvious, so natural, that you wonder why it took so long for Microsoft to implement it. One of those features in SQL Server 2005 is the optional length parameter in the SUBSTRING function. It has long been one of those questions when you wrote a SUBSTRING expression when you wanted to go from the Nth character to the end of the string, how many characters do you want? And for the most part, it didn’t really matter.

But sometimes it did (especially when dealing with nvarchar(max) data.

I learned about this when putting together an update to my Teaching Old Dogs New Tricks presentation. This capability is pretty nifty and something I wish I had a while ago.

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The Scope of ##MS_DatabaseManager##’s Exposure

Published 2026-04-09 by Kevin Feasel

Andreas Wolter expands upon a prior post:

In my previous post (SQL Server Privilege Escalation via DatabaseManager-role: Newly discovered Attack Paths Explained), I showed how a privilege escalation can be achieved by modifying a stored procedure in msdb, based on research shared by Emad Al-Mousa.

When I looked into this more closely, it became clear pretty quickly:
It is not just about a few specific procedures.

Mind you, Andreas is not some kind of shrinking violet, and he was involved in the creation of this role in the first place. There are approximately zero people outside of Microsoft (and the number inside I could probably count on one hand) I would trust more to understand the nature and scope of this issue. This is definitely worth reading.

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