or: How I learned to stop worrying, and love all-caps domain names.
I’m a complete beginner at Linux, so I should preface this post with the fact that these are my humble notes after hours of pulling my hair. It’s not really a fully-fledged how-to article, and there are lot of things I’m not covering. But I figured it may help someone out there at some point.
Continue readingWhenever SQL Server needs to sort a data stream, it will use the Sort operator to reorder the rows of the stream. Sorting data is an expensive operation because it entails loading part or all of the data into memory and shifting that data back and forth a couple of times. The only time SQL Server doesn’t sort the data is when it already knows the data to be ordered correctly, like when it has already passed a Sort operator or it’s reading from an appropriately sorted index.
But what happens if the data is ordered correctly, but SQL Server doesn’t know about it? Let’s find out.
Continue readingWatching Brent Ozar’s 2017 PASS Summit session on Youtube the other day, I learned that the Top N Sort operation in SQL Server behaves dramatically differently, depending on how many rows you want from the TOP.
Continue readingMetadata changes, like modifying a clustered index, or many types of column changes, will create locks in SQL Server that will block users from working with that table until the change is completed. In many cases, those locks will extend to the system objects, so you won’t even be able to expand the “Tables” or “Views” nodes in Management Studio.
I want to show you how you can perform those changes using a copy of the table, then instantly switching the table with the copy. The secret is partition switching, and contrary to popular belief, you won’t need Enterprise Edition, or even partitions, to do it.
Continue readingI’ve solved this puzzle a number of times, but I’ve never really been quite happy with the result. It was either too slow, too much code, too hard to understand. So here’s a fresh take at computing the time-to-payment on a large amount of invoices, with multiple, overlapping, partial payments.
Continue readingThis insanely cool new performance-related update is one of nicest features in SQL Server 2019, and certainly one I’ve been looking forward to for a long time.
If you’ve done any work around performance tuning and user-defined scalar functions, I’m pretty sure you’ll love this.
Continue readingSome operations in SQL Server will turn your entire query plan serial (single-threaded), others will just reserve a so-called “serial zone”. I read up on this stuff a number of years ago (including a great post by Paul White), and thinking that some things must have changed since, I decided to go see for myself.
I’m trying a new type of blog post, and if it works out, I would be happy to post more of the same going forward. The format is a real-world troubleshooting mystery, and I’ll clue you in to the details along the way.
How quickly can you crack it?
Scalar functions can be a real headache when you’re performance tuning. For one, they don’t parallelize. In fact, if you use a scalar function in a computed column, it will prevent any query that uses that table from going parallel – even if you don’t reference that column at all!
Inspired by an actual customer scenario: what if you have a legacy app that doesn’t schema-prefix its database objects, but you want it to work with a specific assigned schema? There’s a quick and easy solution.
