Professional Microsoft SQL Server 2014 Administration by Jorgensen Adam & Ball Bradley & Wort Steven & LoForte Ross & Knight Brian

Author:Jorgensen, Adam & Ball, Bradley & Wort, Steven & LoForte, Ross & Knight, Brian
Language: eng
Format: epub
ISBN: 9781118859193
Publisher: Wiley
Published: 2014-09-07T16:00:00+00:00

SUMMARY

In this chapter, you learned how to read query plans, how queries are processed in SQL Server, and how to identify potential performance improvements. You learned the steps a query goes through when it is compiled and executed: it is parsed into logical operators, optimized into physical operators, and then sent to the execution engine for actual processing. Cost optimization and the impact of the new SQL Server 2014 Cardinality Estimator were discussed. You also learned about the impact of statistics on the Cardinality Estimator, and the value of having updated statistics for accurate query plans.

You learned the impact of various query plan operators on performance, including several data access operators (Table Scan, Index Scan), and several join operators (Hash Join, Nested Loops Join, and Merge Join). This chapter also covered partitioning and its impact on query performance.

Identifying and isolating problem queries should be a standard part of system administration for a SQL Server environment, and Microsoft and other third-party vendors provide many tool sets for monitoring the environment and measuring performance. You learned that the Extended Events monitoring tool can provide a lot of detail that can be used to troubleshoot performance problems, and that the key is understanding expected behavior versus unexpected behavior. You also learned that system DMVs are useful for monitoring query recompile activity.

Now that you understand the basics of SQL performance tuning, you can move to Chapter 14, in which you learn more about creating indexes that will help your query performance.

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