Some time ago, the tab completion code for the SET command was changed to read
the list of available settings from the pg_settings table. This means that
by the time you're done completing SET TRANSACTION ISOLATION, you've already
sent a query and the command will be disallowed. It's not a major issue, but
I figured I'd mention it since it confused me a while ago. If someone has an
ingenious plan for working around this, let me know.
--
Peter Eisentraut
http://developer.postgresql.org/~petere/
