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EXPLAIN FORMAT=JSON has details for subqueries in HAVING, nested selects and subqueries that update values

 | January 25, 2016 |  Posted In: EXPLAIN, EXPLAIN FORMAT=JSON is cool!, MySQL

Over several previous blog posts, we’ve already discussed what information the  EXPLAIN FORMAT=JSON output provides for some subqueries. You can review those discussions here, here and here. EXPLAIN FORMAT=JSON shows many details that you can’t get with other commands. Let’s now finish this topic and discuss the output for the rest of the subquery types. First, let’s look at the subquery […]

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Advanced Query Tuning in MySQL 5.6 and MySQL 5.7 Webinar: Q&A

 | August 24, 2015 |  Posted In: MySQL, Technical Webinars

Thank you for attending my July 22 webinar titled “Advanced Query Tuning in MySQL 5.6 and 5.7” (my slides and a replay available here). As promised here is the list of questions and my answers (thank you for your great questions). Q: Here is the explain example:

why is site_id a covered index for […]

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MySQL Webinar: Advanced Query Tuning

 | July 17, 2013 |  Posted In: MySQL, Technical Webinars

On July 24 at 10 a.m. PDT, I will be delivering a Webinar on Advanced MySQL Query Tuning. I will focus on optimizing the common slow queries with group by and order by. Those queries usually create temporary tables and perform a “filesort” operation. I will show how to optimize those queries so that they […]

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