I am upgrading a database from 5.7 to 8.0 in MySQL and ran across this:
How to easily convert utf8 tables to utf8mb4 in MySQL 5.5
I understand converting the schema and tables to utf8mb4 and utf8mb4_unicode_ci but regarding the changing of columns to varchar(191) I was lost. I tried to follow their disclaimer and read the notes but I cannot see if this is actually needed to upgrade…or why it is even listed as a step.
Also, are there any issues that could arise from converting the tables to utf8mb4 from utf8 and just skipping converting the columns to a different type?
Best Answer
No you can change the character set, because you don't come to the limit that is explained in the article.
So if your utf8 column varchar has a size of more than 191 characters, you will get an error when converting, because tf8mb4 needs 4 bytes per characters and that will exceed the limit.
But as you only have 32 and 64 characters you are wide blow the limit of 191