Strange optimization - xmin,xmax compression :)

hello.

i tested how are distributed values xmin,xmax on pages.
in my tables . typically there are no more than 80 records
on pages.

maybe its possible to compress xmin & xmax values to
1 byte/per record (+table of transactions per page)?
its reduce the space when more than 1 record is
from the same transaction.

Testing query:

SELECT
(string_to_array(ctid::text,','))[1] as page
,count(*) as records
,array_upper(array_agg(distinct (xmin::text)),1) as trans
FROM only
"Rejestr stacji do naprawy"
group by
(string_to_array(ctid::text,','))[1]
order by
3 desc

------------
pasman