It’s orthogonal, and also technically incorrect – the row overhead itself is indeed 23 bytes (less NULL bitmap), but it gets aligned to 24 bytes. Run pg_column_

It’s orthogonal, and also technically incorrect – the row overhead itself is indeed 23 bytes (less NULL bitmap), but it gets aligned to 24 bytes. Run pg_column_size(ROW()) if you’d like to check. The fact that this overhead exists has nothing to do with the 8.6 GB of wasted space on the INTs.