Strange optimization - xmin,xmax compression :) - Mailing list pgsql-performance

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

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pasman