We recently migrated the BDR databases from MySQL version 5.5 to 5.7. Here are a couple benefits for us as application developers:
Stricter Data Handling
By default, MySQL 5.7 uses stricter data handling than 5.5, so we don’t have to manually put MySQL into strict mode.
MySQL 5.5’s loose data handling bit us last summer. We have an application where files can be uploaded, and the file names are stored in the database. A user started getting errors trying to upload new files, because the file names were duplicates (all the file names in the database are required to be unique). It turned out that the file names were too long for the field, so they were being truncated and put into the table anyway. Then, duplicate errors were thrown if a new file name truncated to the same name as another truncated file name. After that, we put MySQL into strict mode for some of our databases, but now it will be that way by default.
Support
The second benefit is that Django 2.1 won’t support 5.5 anymore, and MySQL 5.5 will be End-of-Life this year, so this migration gets us on a better-supported version of MySQL.
Now, if only ‘UTF-8’ in MySQL actually meant UTF-8… Actually, MySQL 8.0 was recently released, and it looks like it uses UTF8MB4 (ie. real UTF-8) by default, so that may be helpful in the future when we move to 8.0.