Hello Pavel,
> The @1 area is partially solved by psql session variables or by pgAdmin
> scripting functionality. @2 is partially solved by GUC but without
> possibility to set a access rights.
>
> I didn't found any implementation of XA variables [...]
I did: GUCs in PostgreSQL are an implementation of transactional session
variables.
As I wrote on the thread, given the "security check" use case, the safe
alternative to transactional session variables is to have nested
transactions. This seems like a far away prospect for pg, but is a reality
for Oracle, DB2 and some others that have untransactional session
variables, so at least it is safe in their case, if not elegant.
My "hard" opinion is that providing an unsafe by default feature (i.e.
which works as in some particular cases, but may fail silently if the
transaction fails), especially for a security related use case which
motivates the whole feature addition, is a very bad idea for the product.
If a committer likes it anyway, good for you.
Other opinions I expressed on the thread are somehow "softer", i.e. even
if I think that there are better (simpler, easier) alternatives, these are
only alternatives.
--
Fabien.