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July 12, 2018

Subqueries, Update Performance, Private Temporary Tables, & Analytic Functions
In July's session we mainly looked at performance. Highlights include:

1:30 How does the database process subqueries?
5:20 Performance: comparing insert ... select to create tmp table, insert select from tmp; DDL in PL/SQL; dynamic SQL problems
12:45 18c private temporary tables; tables specific to a session; DDL you can rollback across!
21:00 Improving update performance: things to watch for; insert vs. update; "join-update" - create a view instead; create table as select "update"
34:05 Analytic function performance: first_value non-determinism; min keep vs first_value; computing function in a subquery; indexes for analytic functions

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Experts

Your Experts
Chris Saxon
Chris Saxon, Oracle Developer Advocate for SQL    
Chris Saxon is the quizmaster for the Database Design competitions and an Oracle Developer Advocate for SQL. His job is to help you get the best out of the Oracle Database and have fun with SQL! He's also part of the answer team on Ask TOM and creates YouTube videos at The Magic of SQL channel.
Keith Laker
Keith Laker, Senior Principal Product Manager    
I have been working with Oracle data warehouse technology for over 20 years working on a wide variety of data warehouse projects both as a consultant and an onsite support engineer. I am now part of the Data Warehouse Product Management Team where I am responsible for analytical SQL. I am based in the UK at our Manchester office. A key part of my role is to work with our sales teams to brief our customers on data warehousing and analytical SQL: explaining the wide variety of new and exciting opportunities that our DW and analytical solutions can support. I regularly deliver sales training for data warehousing and analytical SQL across all our sales regions and provide competitive intelligence support across all the major data warehouse vendors.