Databases Reference
In-Depth Information
7
Latches and Spinlocks
WHAT'S IN THIS CHAPTER?
➤
Recognizing the symptoms of latch and spinlock contention
➤
Describing the types of systems which are susceptible to latch and
spinlock contention
➤
Descriptions of latch types and modes
➤
Common contention-prone scenarios and how to resolve them
WROX.COM CODE DOWNLOADS FOR THIS CHAPTER
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on the Download Code tab. The code is in the Chapter 7 download
and individually named according to the names throughout the chapter.
OVERVIEW
When I speak to database consultants, many of them are familiar with SQL Server's locking
behavior, and can even describe many of the principles covered in Chapter 6. They're far less
coni dent about latches, however. Similarly, comparatively few can talk at any length about
spinlocks, which are a very related topic. In light of this, I consider this chapter to be an
important inclusion in this topic.
The idea of this chapter is to offer practical advice to users trying to resolve issues identii ed to
be related to both latch and spinlock behavior. We begin by describing some of the scenarios
you might i nd yourself in, and the kind of symptoms you might see that betray a latch or
spinlock problem. Even if they all seem alien (you might have never yet experienced latch
contention) it would be useful to have a passing familiarity with these symptoms so that you
can recognize various problems when you see them. By looking at the kinds of environments
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