SQL Server Execution Plans - Red Gate Software

Chapter 8: Advanced Topics
In the previous chapters, we have discussed how the optimizer generates execution plans
and how to interpret them, and we have examined plans for some moderately complex
queries, including most of the common SQL Server objects, such as stored procedures,
views, indexes, cursors, and so on. In our discussion of hints, we even walked through
some ways in which we could exercise a measure of control over how the optimizer
generates an execution plan.
In this chapter, we will take a tour of some of the more advanced topics related to the
interpretation and manipulation of execution plans, covering the points below.
• Large-scale execution plans – How to interpret them.
• Parallelism – Why you might want to use parallelism, how to control it in your query
execution and how to interpret parallel plans.
• Forced parameterization – Used to replace hard-coded literals with parameters
and maximize the possibility of plan reuse; used mainly in systems subject to a large
amount of ad hoc, or client-generated T-SQL.
• Using plan guides – To exercise control over a query through hints without changing
the actual code; an invaluable tool when dealing with third-party applications.
• Using plan forcing – To capture and reuse an execution plan, the final word in
controlling many of the decisions made by the optimizer.
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