Re: primary key charset latin1 and other columns utf8 for performance?

[Rick James]

Another performance aspect...
Smaller -> more cacheable & less I/O -> faster
That is BINARY(16) is the smallest, so it is the fastest.
VARBINARY(32) utf8 is the slowest.

VAR is not needed, assuming these are constant length.
VAR has a small overhead.

Hash/GUIDs/UUIDsMD5/etc have a serious performance issue for _large_ tables -- they are very random. When the table is much larger than RAM, INSERTing one row will take (about) one disk hit to randomly update the index. On typical drives, you can get only 100 disk hits/second.