Why don BEGIN, ROLLBACK and COMMIT work in stored procedures/functions?
PostgreSQL doesn’t support autonomous transactions in its stored functions. Like all PostgreSQL queries, stored functions always run in a transaction and cannot operate outside a transaction. If you need a stored procedure to manage transactions, you can look into the dblink interface or do the work from a client-side script instead. In some cases you can do what you need to using exception blocks in PL/PgSQL, because each BEGIN/EXCEPTION/END block creates a subtransaction.
