Summary
The SQL Server query processor typically selects a good execution plan for your queries, but there may still be cases when, even after extensive troubleshooting, you do not get good performance from a selected plan. Query optimization is an inherently complex problem, and despite several decades of query optimization research, challenges in some fundamental areas are still being addressed today.
This chapter provided recommendations on what to do when SQL Server is not giving you a good execution plan. One such methodology, which you can use in cases when the SQL Server query optimizer can’t produce a good plan for complex queries, is to break these queries down into two or more simpler queries while storing the intermediate results in temporary tables.
Although hints can be used to improve the performance of a query in these cases by directly taking control of the execution plan selection, they should always be used with caution, and only as a last resort. You...
