I am trying to benchmark postgres (17) on ZFS (ubuntu). I created a partitioned table and want to see the actual number of bytes required to store the data on the table. I am under the impression though that something like

   SELECT inhrelid::regclass AS partition_name, 
   pg_size_pretty(pg_table_size(inhrelid::regclass))
   FROM pg_inherits
   WHERE inhparent = 'my_table'::regclass;

does not show the correct size. Seems that I am other getting the uncompressed size, or something is really wrong. (On ext4 the table is around 3MB in total).

any idea on how I can check what the compression benefits I get are?