So it seems to me that we pretty much already made a decision that the controlling definition of DISCARD ALL is that, as the fine manual says "DISCARD ALL resets a session to its original state". Whatever decision we make now ought to be consistent with that.
IOW, I don't care whether we introduce a new subcommand or not. But I *do* think that that we ought to make our best effort to have DISCARD ALL clear everything that smells like session-local state. Random incompatibilities between what you see when running under a connection pooler and what you see when connecting the DB directly are *bad*, regardless of whether a well-designed application should be relying on those particular things or not. The whole point of having a transparent connection pooler is that it's supposed to be transparent to the application.
+1
The attached wip patch do that and introduce a subcommand 'SEQUENCES', but if we decide to don't add a new subcommand to DISCARD, then its easier to modify the patch.
