October 2003
Intermediate to advanced
1072 pages
24h 21m
English
Content preview from Guru's Guide to SQL Server Architecture and Internals, TheBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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Parameter Sniffing
Prior to compiling an execution plan for a stored procedure, SQL Server attempts to “sniff” (i.e., discern) the values of the parameters being passed into it and use those values when compiling the plan. When these values are being used to filter a query (i.e., as part of a WHERE or HAVING predicate), this allows the optimizer to produce a more precise execution plan tailored to the values being passed into the stored procedure (using the statistics histograms for the columns they're used to filter) rather than based solely on the average density of the relevant table columns. Generally speaking, this is a good thing and results in improved performance over older versions of SQL Server.
You can get into trouble, however, when ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.