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Distributed Replay Deprecated in SQL Server 2022

Brent Ozar starts the wake:

For SQL Server 2022, Microsoft deprecated Distributed Replay.

The idea behind the feature was that you’d capture a trace against your production environment, set up another environment for load testing or QA testing, and then replay that exact same workload against it. You’d be able to measure which queries got better or worse, and how.

The reality was a complete mess. It was a giant pain in the rear to set up and use, to the point where I got frustrated with it within a few hours and asked my peers about their experiences with it. I got back a string of four-letter words – everybody really struggled to get it across the finish line. Over subsequent versions, Microsoft made token efforts to improve it, but never really gave it the love it required.

Yep, I can concur. What we wanted was a simple button-click (or easy-to-navigate UI) that let you capture “What does a real production workload look like?” and then the ability to re-run it elsewhere, like on new hardware. What we got was indeed a mess.

I don’t fully agree with Brent’s argument that the right answer is to build app-level testing. If everything was architected and developed for this, then yeah, that might be a better answer. But unless you’ve built all relevant applications around APIs (so they can be programmatically invoked rather than trying to do everything via Selenium) and have put in the legwork necessary to track and re-run calls, I think you end up with an even bigger mess—especially if there are multiple applications working with the same database. I do agree that this is a hard problem regardless of the path you choose.

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