Writing optimal queries
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Writing optimal queries requires considering things like using functions properly, avoiding data type mismatches, ensuring join predicates and statistics are defined, and addressing issues like clustered GUIDs. Developers should also avoid anti-patterns like using temp tables unnecessarily, putting filters in HAVING that could go in WHERE, and handling multiple aggregates carefully. The document provides tips for writing efficient queries from Sourabh Agarwal, a Microsoft premier field engineer who blogs and is active on Facebook and Twitter regarding SQL Server topics.
Writing optimal queries
- 2. Things to Consider • Using Functions in Queries • Implicit Conversions/Data Type Mismatch • Missing Join Predicates, Missing Column Statistics • Clustered GUID’s • Remember - Row goal issue
- 3. Things to Consider contd.. • SQL Anti Patterns • Temp Table vs Table Variable • Avoid using HAVING when its possible to use WHERE • Issues with Multiple Distinct Aggregates.
- 4. Introduction • Sourabh Agarwal • Premier Field Engineer – Microsoft Services • Blogs: www.sqluninterrupted.com • Facebook: www.facebook.comtroubleshootingsql, www.facebook.comsqlserverfaq, https://www.facebook.com/groups/SQLBangalore/?ref=bookmarks • Twitter: @SQLSourabh