Beginning Microsoft SQL Server 2008 ... - S3 Tech Training

Figure 12-1
Time of Creation
At Execution
First run/
Recompile
Not first run, but not in cache
Not first run and in cache
Added to the
procedure cache in
memory
Chapter 12: Stored Procedures
Added to:
sysobjects
sysdepends
syscomments
Optimized and compiled
Recompiled
After the sproc has been created, it sits in wait for the first time that it is executed. At that time, the sproc
is optimized and a query plan is compiled and cached on the system. Subsequent times that we run our
sproc will, unless we specify otherwise using the WITH RECOMPILE option, generally use that cached
query plan rather than creating a new one. (There are situations where the sproc will be recompiled, but
that is beyond the scope of this book.) This means that whenever the sproc is used it can skip much of
the optimization and compilation process. Exactly how much time this saves varies depending on the
complexity of the batch, the size of the tables involved in the batch, and the number of indexes on each
table. Usually, the amount of time saved is seemingly small — say, perhaps 1 second or less for most
scenarios — yet that difference can really add up in terms of percentage (1 second is still 100 percent
faster than 2 seconds). The difference can become even more extreme when we need to make several
calls or when we are in a looping situation.
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