July 2012
Intermediate to advanced
478 pages
10h 3m
English
Content preview from Microsoft SQL Server 2012 Performance Tuning CookbookBecome 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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Find out-of-date statistics and get it correct
The statistics object is the major source of information about data distribution for the predicate. Without knowing the exact data distribution, the query optimizer cannot have cardinality estimation, which is the process of calculating number of rows to return by applying the predicate.
After creating the statistics for the column, the column becomes out-of-date after executing DML commands, such as INSERT, UPDATE, and DELETE, because these commands change data, thereby affecting data distribution. In this scenario, a statistics update is needed.
In highly active tables, statistics become outdated in maybe a few hours; for static tables, statistics become outdated maybe in a few weeks. The decision ...
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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.
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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.