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Video training update 2025

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There have not been any updates for the SQLServerFast Execution Plan Video Training for a long time. In fact, it’s already over one and a half year since the last set of videos was released! But that is not because I have been sitting still. I have, in fact, done a lot of work between then and now, even though the effects of all that work might not have been very visible. Changed plans After completing and releasing block 3 (Combining data), I started working on the next planned block, which would have been block 4 (Sorting and grouping). But…
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A rather failed attempt to have AI render an image where four matches are arranged in the form of the hashtag (pound) symbol.,

A deep dive into hash tables, part 2

In part 1 of this series, I laid the foundation to explore the structure of the hash table, as used by the Hash Match operator, by alleging and then proving that a Hash Match (Left Outer Join) returns unmatched rows from the build input in the order in which they are stored in the hash table. This means that we can create queries on carefully curated data to gain insight in the structure of that hash table. It is now time to use that trick to actually start to explore the hash table. But not without also looking at available…
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A deep dive into hash tables, part 1

We all know the Hash Match operator. It joins or aggregates data, based on a hash table. That hash table is ideally stored in memory. But if the granted memory is insufficient, then Hash Match will spill to tempdb, which is slow. I assume that every reader of this blog knows this already. But what you probably don’t know is how that hash table is structured. How is the data stored? Where are new rows added, how is the table accessed? To be fair, none of this is useful knowledge, unless you work for the engine team at Microsoft. And…
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T-SQL Tuesday 183 – Permission hell

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The 183rd edition of T-SQL Tuesday is hosted by Steve Jones. He has picked everyone’s favorite (cough) topic: permissions, and how to manage them. I am lucky. With my specialization in query performance tuning, I don’t often have to deal with permissions. (Well, apart from of course not getting the permissions I need to do my work effectively). But I have been in contracts where I was the only employee able to spell SQL, and hence all other database tasks also fell in my lap. Including permissions. And yes. I have been in projects where the idea was to investigate…
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T-SQL Tuesday 182 – Integrity

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(I wrote this well in time. Really. I swear. And then … forgot to publish it in time. Oh well. This will then be my T-SQL Wednesday, I guess?) Welcome to the first T-SQL Tuesday of 2025. Hosting duty this time falls on Rob Farley’s shoulders. And he has found a great topic: Integrity. I really love this topic, because, as Rob himself also acknowledges and explains, that single word can mean many things in the Data Platform community. With this being a technical blog, by someone who loves not only execution plans but also data modelling and database design,…
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T-SQL Tuesday 181 – Amazing announcements

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It’s December. The last month of the year, and hence also the last T-SQL Tuesday of the year. Edition 181 is hosted by Kevin Chant. His chosen topic for this episode is to have us talk about which SQL Server announcement excited us the most. This posed a bit of a problem for me. The only truthful answer here is that I have never been as excited about an announced new feature as when the Query Store was announced. But I also realized that I don’t have much to write about the Query Store, except how awesome it is. Okay,…
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T-SQL Tuesday 180 – The enemy of good?

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Another month, another T-SQL Tuesday. Edition 180 already. Our host is Josephine Bush, and she opens a topic that hits close to home for me: is good enough, perfect? I know my weaknesses. I know that my perfectionism is one of them. I know that striving for perfect is not always the best thing to do. I know that perfect is the enemy of good enough. And yet, I also embrace my perfectionism, allow myself to indulge in it … at the right time. Sometimes, good is good enough I am a consultant. Customers pay me money in exchange for…
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Black Friday again

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November is near. Traditionally (in the USA, at least) the month of the Black Friday sales. I have decided to once more join in on that tradition! During the entire month November 2024, I offer a 50% discount on all prices for the SQLServerFast Execution Plan Video Training. And that discount even stacks with the 10% discount code you might have from attending one of my conference sessions, or with the 20% discount code you get when you attend my pre-con! So that is at least half off for everyone, and even more off for some! Execution plan training has…
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T-SQL Tuesday 178 – Misleading data in Query Store

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This post is for T-SQL Tuesday 178, hosted by Deepthi Goguri. She invites us to write about a recent technical issue we resolved. So let’s talk about the time I discovered that information in the Query Store might not be what it appears to be. Unexpected delays I was hired by a customer who had a very annoying issue with the daily data load of their data warehouse. The volume of data to be loaded is high and they were already struggling to finish the load before business opens. But that was not their biggest issue. The biggest problem, the…
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Plansplaining part 33 – Fast forward cursors

Welcome back to my plansplaining blog series, where I dissect execution plans in order to increase our understanding of how SQL Server processes specific queries. We’re at part 33 already, and I’m still looking at cursors. After discussing the basics, static cursors, dynamic cursors, and keyset cursors, I will now look at the last of the cursor types: the fast forward cursor. Fast forward cursor One of the things that has always bothered me about the fast forward cursor type is the shocking lack of documentation of what it does exactly. Okay, the name suggests that it is fast. But…
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