TSQL Performance Tips

SQL Server optimizer doesn't use and index seek for execution of your query although the quer is high selective? What is better, when and why: LIKE vs: SUBSTRING, IN vs. EXISTS, SUBQUERY vs. JOIN. Why you should not use the UPPER or LOWER functions? How to avoid non-SARG-able WHERE clauses? Which query takes about 3 minutes in SQL Server 2008 and only one second in SQL Server 2012?

In this session we will answer these questions and show how bad designed queries lead to poor execution plans. We will offer recommendations and tips how to avoid performance problems caused by poor query design (functions in WHERE clause, data type conversions…) and explain how local variables and parameters affect the generation of execution plan. We will discuss and compare different query approaches and operators (IN vs. EXISTS, EXISTS vs. COUNT(*), UNION vs. UNION ALL, IN vs. BETWEEN…)  and give appropriate recommendations. We’ll also cover database constraints from the performance point of view.
Presented by Milos Radivojevic at SQLBits X
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  • SpeakerBIO

    Milos Radivojevic is a database developer, consultant, speaker, and trainer located in Vienna, Austria. He has been working with SQL Server over 15 years. He is Microsoft SQL Server MVP and MCT and specializes in SQL Server for application developers and performance and query tuning. Currently he works as principal database consultant in bwin.party (the largest regulated online gaming company in the world) where he works with some of the largest SQL Server databases. He is co-leader of the SQL Server PASS Austria. He is a speaker in international conferences (SQLBits, SQL Saturday, Sinergija, SQL Conference) and speaks regularly at SQL Server PASS Austria meetings. His Twitter handle is @MilosSQL.

    http://www.bwinparty.com http://milossql.wordpress.com/feed
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