1 query, 3 parameters, 3 different plans

Parameter Sniffing in SQL Server 2019: Adaptive Joins

So far, I’ve talked about how adaptive memory grants both help and worsen parameter sniffing, and how the new air_quote_actual plans don’t accurately show what happened. But so far, I’ve been using a simple one-table query – let’s see what happens when I add a join and a supporting index: Transact-SQL CREATE INDEX IX_OwnerUserId_Includes ON…
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Adaptive Blog Posts

It turns out I can be dumb In a previous blog post about Adaptive Joins, I thought that EXISTS wasn’t supported by the new feature. It turns out that EXISTS is totally 100% supported, as long as your indexes support EXISTS. To show this, I need to show you a query that gets an Adaptive…
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Adaptive Joins And SARGability

There’s a famous saying Non-SARGable predicates don’t get missing index requests. And that’s true! But can they also stifle my favorite thing to happen to SQL Server since, well, last week? You betcha!© One Sided I’m going to paste in some queries, each with something non-SARGable. There are two tables involved: Users and Posts. Only…
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The 2017 Adaptive Join Optimization Eats Bad TSQL For Breakfast

Cheeky If you thought that title sounded familiar, you sure were right. That’s called a classical reference. So here we are, three whole years later, and yet another improvement to the engine promises to fix performance issues forever and ever. While this isn’t exactly an entirely new cardinality estimator, it’s an entirely new branch in…
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