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Day: July 9, 2026

Red Flags in Query Design

Published 2026-07-09 by Kevin Feasel

Thomas Williams has a list:

Nowadays I look after 3rd-party databases more than internally-developed ones, so I accept there’s a whole lot of ex-best practices, vendor preferences, and possibly shortcuts in queries I might come across – whether it’s a poorly-performing query, a blocker, or an error.

(Although, when I developed software more frequently, I was guilty of all the gripes below. My start in SQL, last century, was poring over a big yellow “For Dummies” book. I was the dummy.)

Click through for the list. I particularly hate tibbling, a rather derisive term for the malformed version of Hungarian notation. This would just lead me down a rant about how systems Hungarian notation was a mess, whereas apps Hungarian notation can be useful in certain circumstances. Tibbling provides no semantically valuable information, which is why I dislike it so much.

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JSON Index Testing in SQL Server 2025

Published 2026-07-09 by Kevin Feasel

Reitse Eskens gives it a whirl:

In today’s cloud era, Azure SQL is usually first with new functionality, while on-premises SQL Server follows. One of the new things is the JSON data type and accompanying JSON index.

Because I had to learn how JSON works in SQL Server for my DP-800 exam, I decided to see how the JSON index works and when it works. I’ll go into the execution plans, some details, and check out the statistics when a query runs. Just so you know, this is much deeper than the certification requires, so no need to get this all in your head for the exam.

Click through for a rundown of how this feature works on-premises and what you should be on the lookout for.

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Solving the Maximum Flow Problem in T-SQL

Published 2026-07-09 by Kevin Feasel

Sebastiao Pereira implements the Ford-Fulkerson algorithm:

Graphs can be used to formulate mathematical models for many different applications and one particular type of problem to be solved deals with networks that transport some kind of resource from one endpoint to another, like water or electricity. Is it possible to create using only SQL Server features?

What’s neat about this is that this sort of flow algorithm also works for, say, complex ETL processes. Also, in case you were as curious as I was, that map is Dresden.

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T-SQL Code Smells

Published 2026-07-09 by Kevin Feasel

Rob Farley has a few:

I feel like I should preface this with a disclaimer. I added “potentially-” to the title, because there are many queries that might seem bad but can actually perform just fine. There are queries that on the surface can be great, but are nasty without a particular index, and there are queries that make me cringe a little when looking at them, but are actually okay. Brent Ozar is asking about signs of bad code for this month’s T-SQL Tuesday (the 200th – and I have a response for all 200 if you look back through my history of posts), and he wants us to write this for 2004 Brent, rather than 2026 Brent.

Click through for what Rob has come up with. I agree with all of Rob’s examples and do appreciate his usage of the APPLY operator as a way of solving one common problem.

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The Never-Ending Query

Published 2026-07-09 by Kevin Feasel

Andy Yun doesn’t like it:

You know THE ONE I’m talking about… it has numerous sub-queries and CTEs… JOIN after JOIN after JOIN… predicates within predicates. Or maybe it’s just an obscene MERGE statement. 

These are particularly painful to deal with because it’s hard to test the pieces in isolation and ensure that an issue earlier in the process doesn’t bite you later.

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Traits of Sketchy Queries

Published 2026-07-09 by Kevin Feasel

Louis Davidson has a list of red flags in code:

I still feel like garbage, so I decided just a simple list would do. I will also preface this by saying each item could include “without a coherent comment.”

Everything on this list fills me with dread unless I read someone say: “Such and such was needed because the optimizer wouldn’t….” and then I at least know why they believed needed it.

Click through for Louis’s list. Most of these aren’t bad things per se, but they do serve as signs of a potential deeper issue.

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