--;;-- load-session
select expiration , store 
  from session_t 
 where session_uuid = ?uuid 

--;;-- make-session!
insert into session_t
     ( session_uuid , expiration , store ) 
select a.uuid , a.expiration , a.store 
  from (select ?uuid::varchar(36) as uuid , ?expiration::double precision as expiration , ?store::text as store) a
  left join session_t s
    on a.uuid = s.session_uuid 
 where s.session_uuid is NULL 

--;;-- save-session!
update session_t 
   set expiration = ?expiration 
     , store = ?store 
 where session_uuid = ?uuid 

--;;-- destroy-session!
delete from session_t 
 where session_uuid = ?uuid