A Where Clause Problem Recompile Doesn’t Fix

Fast 1

After blogging recently (maybe?) about filters, there was a Stack Exchange question about a performance issue when a variable was declared with a max type.

After looking at it for a minute, I realized that I had never actually checked to see if a recompile hint would allow the optimizer more freedom when dealing with them.

    ON dbo.Users(DisplayName);

DECLARE @d nvarchar(MAX) = N'Jon Skeet';

    COUNT_BIG(*) AS records
FROM dbo.Users AS u
WHERE u.DisplayName = @d;

    COUNT_BIG(*) AS records
FROM dbo.Users AS u
WHERE u.DisplayName = @d

Turns out that it won’t, which is surprising.

happy cheese

Even though both plans have sort of a weird seek, the filter operator remains as a weird sort of residual predicate.

truly try me

Thanks for reading!

A Word From Our Sponsors

First, a huge thank you to everyone who has bought my training so far. You all are incredible, and I owe all of you a drink.

Your support means a lot to me, and allows me to do nice stuff for other people, like give training away for free.

So far, I’ve donated $45k (!!!) worth of training to folks in need, no questions asked.

Next year, I’d like to keep doing the same thing. I’d also like to produce a whole lot more training to add value to the money you spend. In order to do that, I need to take time off from consulting, which isn’t easy to do. I’m not crying poor, but saying no to work for chunks of time isn’t easy for a one-person party.

I’m hoping that I can make enough in training bucks to make that possible.

Because this sale is extra sale-y, I’ve decided to name it after the blackest black known to man.

From today until December 31st, you can get all 25 hours of my recorded training content for just $100.00. If you click the link below to add everything to your cart, and use the discount code AllFor100 to apply a discount to your cart.




Some fine print: It only works if you add EVERYTHING. It’s a fixed amount discount code that you need to spend a certain amount to have kick in.

Thank for reading, and for your support.

2 thoughts on “A Where Clause Problem Recompile Doesn’t Fix

Leave a Reply

Your email address will not be published. Required fields are marked *