select provariadic,oid, proname from pg_proc where arraycontains(proargmodes::char[],ARRAY['v'::char]) order by oid;
select prokind,length(prokind),count(*) from pg_proc where oid < 16384 group by prokind;

-- The structure of function standby_statement_history must be consistent with table statement_history.
select
    (select relnatts from pg_class where relname = 'statement_history' limit 1)
    =
    (select array_length(proargnames, 1) - 1 from pg_proc where proname = 'standby_statement_history' order by 1 limit 1)
    as issame;