Re: "Specified key was too long. Max key length is 500" with a ALTER statement

[Rick James]

Plan A: recompile MySQL 3 to change the 500. (I assume it was a defined constant in the code.)

Plan B: use VARCHAR(249) instead of 255.

Plan C: use prefix on index (if you need the index), then do the UNIQUEness constraint in your code.

utf8 complicates things (beginning in ~4.1) because the 255 needs to be tripled when computing index size. But maybe you could limit that name and module be to ascii, not utf8.