Maxim Orlov <orlovmg@gmail.com> writes:
> 1) Can this behaviour, in the case described above, when after dump and
> recovery we receive different data, be considered correct?
It's undesirable, for sure.
> 4) Does it make sense to extend the "simple case" grammar so that it can
> accept a custom operator?
This has been discussed before, see e.g. [1][2]. Unfortunately CASE
is just the tip of the iceberg, there are several SQL constructs that
are equally underspecified. Fixing them all looks messy, and it would
cause dumps to be even less portable than they are now. So nobody's
stepped up to tackle the issue.
regards, tom lane
[1] https://www.postgresql.org/message-id/flat/20141009200031.25464.53769%40wrigleys.postgresql.org
[2] https://www.postgresql.org/message-id/flat/10492.1531515255%40sss.pgh.pa.us#8755318d9b16ec32296398f0893a44d7
