I have a Golang program that may connect to databases with different character sets or collation.
For example the default at the time of writing of the Golang MYSQL driver is utf8mb4_general_ci https://github.com/go-sql-driver/mysql#collation
However if I connect to a database configured like so:
CREATE DATABASE example character set utf8mb4 collate utf8mb4_unicode_ci;
Can I expect "bad things to happen"? Indexes not to work?
In most case, there are no problem. For example, column collation is used regardless connection collation when WHERE column=? is used.
See also: https://dev.mysql.com/doc/refman/5.6/en/charset-collation-coercibility.html
But I can't speak it's 100% safe. It's safe to use one collation all place.