Kovács Zoltán <kovzol@particio.com> writes:
> What can happen if I use an unsafe combination? Can the backend unexpectedly
> die? Can this cause data corruption?
Inconsistent ordering results and index corruption can be expected at
minimum. I'm not sure about actual crashes. Try looking through
the pgsql-bugs archives for related problem reports from PG versions
that didn't have the locale compatibility checks.
regards, tom lane