PostgreSQL multiple transactions on the same connection
postgresql
Solution
If with unrelated you mean one after the other, then the answer is yes.
If you mean having different transactions open at the same time, then the answer is no (there are some hacks available using dblink but I don't think they qualify as "on the same connection).
Problem
Does PostgreSQL support multiple transactions on the same connection? I don't mean nested transactions, but unrelated different transactions.