Slides and audio: How MySQL Handles ORDER BY, GROUP BY, and DISTINCT

I haven’t posted anything for a while, but that doesn’t mean that nothing was happening around MySQL Optimizer. In fact, exactly the reverse was true - so many thing were happening that I didn’t have time to blog.

I’ll try to make up for the lost coverage. Let’s start from smaller things. On Nov, 1 I’ve had a MySQL University session titled How MySQL Handles ORDER BY, GROUP BY, and DISTINCT.

The session page has slides and audio. If you’re ready to spend 1 hour on MySQL’s ways of doing ordering, you can listen to the audio. Otherwise, you can just scroll through the slides. They are reasonably self-contained and explain MySQL’s ORDER BY and GROUP BY handling in easy-to-digest colorful pictures.

Posted in how-it-works on December 8th, 2007 by spetrunia | |

2 Responses to ' Slides and audio: How MySQL Handles ORDER BY, GROUP BY, and DISTINCT '

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  1. on December 14th, 2007 at 10:35 pm

    […] Sergey Petrunia makes available audio and slides from his presentation, How MySQL Handles ORDER BY, GROUP BY, and DISTINCT. […]

  2. Rick James said,

    on September 27th, 2008 at 10:06 am

    What about ORDER BY NULL ? It turns off certain sorts? Perhaps even the “ORDER BY group_by_list is guaranteed for free” (slide 12)?

    Won’t GROUP BY sometimes use a hash, thereby have to do extra work to guarantee ORDER BY?

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