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Author: Kevin Feasel

What’s Missing in Columnstore Indexes

Published 2025-12-08 by Kevin Feasel

Niko Neugebauer has a list:

After spending some time thinking about the best way to come back to writing about Columnstore Indexes, after 5 and half years hiatus, I came to a conclusion that I have never published a post on what is still missing. With that in mind, I decided to mark my comeback to writing technical posts on my blog with rather simple post on the things that are needed, but did not made into the SQL Server – based engines so far (as of December 2025).

Niko has seven items on his list. I tend not to cover wish lists on Curated SQL, but when it’s Niko and columnstore indexes, I’m willing to make an exception.

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When IQP Features Make Things Worse

Published 2025-12-08 by Kevin Feasel

Rebecca Lewis has a two-parter. First up is a post covering the guard rails available in IQP:

When Microsoft introduced Intelligent Query Processing in SQL Server 2019 and expanded it in SQL Server 2022 and 2025, the message was simple: upgrade, enable the right compatibility level, and the optimizer will quietly make your queries faster. Features like batch mode on rowstore, memory grant feedback, scalar UDF inlining, and parameter-sensitive plan (PSP) optimization all promise “automatic performance.”

But buried in Microsoft’s documentation is a reality worth understanding: Some IQP features can reduce or discontinue feedback when performance becomes unstable. This is intentional. IQP includes guard rails—safety mechanisms that change or stop certain feedback behaviors if they prove counterproductive.

Part two tells us how to figure out if an IQP feature got the works:

Memory Grant Feedback was introduced in SQL Server 2019 and enhanced in SQL Server 2022+. Microsoft documents several plan attributes that reveal how the engine adjusted or suspended feedback. These attributes appear under the MemoryGrantInfo node in the execution plan.

And stay tuned for part three.

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Scan Types in PostgreSQL

Published 2025-12-08 by Kevin Feasel

Elizabeth Christensen has some neat imagery:

The secret to unlocking performance gains often lies not just in what you ask in a query, but in how Postgres finds the answer. The Postgres EXPLAIN system is great for understanding how data is being queried. One of secretes to reading EXPLAIN plans is understanding the type of scan done to retrieve the data. The scan type can be the difference between a lightning-fast response or a slow query.

Click through for the list, as well as images that clearly explain what’s happening.

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Optimized Locking Slowdowns in SQL Server 2025

Published 2025-12-05 by Kevin Feasel

Rebecca Lewis points out when optimized locking fails:

SQL Server 2025 introduces a feature called Optimized Locking, designed to reduce blocking across read–modify workloads. In many environments it helps, but certain mixed workloads experience longer lock waits, stalled S → U → X transitions, and even occasional threadpool saturation.

My inner 12-year-old has already made about a half-dozen plays on the phrase “When optimized locking SUX.”

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Comparing TRANSLATE() and REPLACE()

Published 2025-12-05 by Kevin Feasel

Louis Davidson is lost in translation:

The data I am working with sometimes has people with multiple parts to their name (Mary Jo, Cindy Lou) etc, or sometimes Fred/Joe, Mary and Jack, Mary & Jack, or what have you. My goal was to turn these names into little delimited lists that I could parse on a space character with STRING_SPLIT and there were a “few” of these cases. This was the code I had arrived at when I reached the “good enough” stage of my coding.

Louis had 19 nested REPLACE() calls, but Certified Good Guy Erik Darling shows him the way.

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Sending E-Mails from Data Factory Pipelines

Published 2025-12-05 by Kevin Feasel

Andy Brownsword glues together a few resources:

Not all pipelines in Azure have native options for sending emails. The lucky Fabric folks have an Office 365 connection ready to rock. Data Factory and Synapse don’t have email capability built-in and need another option to send messages. So for everyone who wants more emails for their inbox rules to handle (delete), we’ll build and call a Logic App.

For this example we’ll have basic email parameters – To, Subject, Body – along with an optional attachment from a storage account. Also note that I’ve left all actions with their default names – if you change them make sure to update expressions accordingly.

Read on to see how it all works.

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Thoughts on Renaming sa

Published 2025-12-05 by Kevin Feasel

Andreas Wolter asks, what is in a name?

This is another one of those subjects that keep circulating: should you rename your sa account?

Plenty of “security check” scripts swear you should. Meanwhile, when you talk to actual humans in the real world, you’ll notice that almost nobody does it. (Funny how that works.)

So what does Sarpedon Quality Lab® recommend – and why? Our answer (read to the end) may surprise you.

Before reading Andreas’s post, I wanted to note that, when I was a DBA and had control of such things, I would actually rename the sa account and then create a separate account called “sa” with zero permissions, not even the ability to connect. I never considered it a critical part of a security posture, but knowing how many scripts try to brute-force an account called sa, I figured setting up a false front like that would add some protection on the margin.

After reading Andreas’s post, I wasn’t aware that doing so would break replication, though it makes sense because I wasn’t using replication at that time. Making sa’s password extremely long is also a good idea.

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The 1600 Column Limit in PostgreSQL

Published 2025-12-05 by Kevin Feasel

Andreas Scherbaum covers a limitation:

A recent blog posting by Frédéric Delacourt (Did you know? Tables in PostgreSQL are limited to 1,600 columns) reminded me once again that in the analytics world customers sometimes ask for more than 1600 columns.

Read on for the technical limitations around how many columns could conceivably fit in a PostgreSQL table. But I will rely here on Swart’s 10% Rule: if you have more than 160 columns on a single table, that’s a sign you should step back and ask why this is the case. Even the widest of data warehousing dimensions is likely to be considerably smaller than this and the smart move is to rethink that data model before agitating for additional columns.

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Comparing JSON Data Types in MySQL and Postgres

Published 2025-12-05 by Kevin Feasel

Aisha Bukar draws some comparisons:

MySQL and PostgreSQL are two of the most popular relational database systems in the world. Both are open-source, widely used in web and enterprise applications, and support structured data in tables.

Modern applications, however, often work with semi-structured data that doesn’t always neatly fit into tables with rows and columns. This type of data gets its name because it still has some organization but doesn’t follow a strict format.

JSON (JavaScript Object Notation) is a popular way to store and share this kind of data. It’s a text format easy for both people and computers to understand.

Read on to see what’s supported in each of these platforms, as well as strengths and limitations of using JSON in each.

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