Hello Christian,
Currently, `bytea` does not have any bitwise logical operations yet. This issue came up in an old thread from 2006 [1], but nobody seemed to have picked this issue so far.
I remember this one because I needed them for checksuming set of rows. There is a whole set of missing (from my point of view) operators, casts and aggregates.
See https://github.com/zx80/pg_comparator where I packaged the subset I needed as an extension. In particular, there is a bitxor which can be used for bytea if casting is allowed.
Tested on PG 9.6. I hope you find this useful.
I think that the probability of getting these useful things into pg is alas small. In the mean time, you may package and register it as an extension?
-- Fabien.
