Notes

Fun MySQL fact of the day: Extra confusing

If, over the last few days, you've started EXPLAINing your queries more, I commend you: you're on the path to becoming a database query optimiser extraordinaire. You may have also identified that the Extra column isn't a singleton value. You may have even seen something weird like Using where; ... read more

Fun MySQL fact of the day: so many index reads

On Friday, we discussed the separate roles that MySQL and InnoDB have while querying data. Specifically, we looked at how InnoDB reads data for MySQL and how MySQL may or may not be tasked with additional filtering of the data. We also briefly discussed how MySQL may choose to ... read more

Fun MySQL fact of the day: OR not

We started discussing secondary indices yesterday, and we considered how we might create two separate indices on our user table. We also started to build an understanding of when MySQL can and shouldn't use an index for a query, but we omitted one fun fact. ... read more
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