heh, my calculation was incorrect: ItemID is 4 bytes in size, so the calculations are slightly off: pre-13 was 16 bytes each (20 when 64-bit compiled), and pos

heh, my calculation was incorrect: ItemID is 4 bytes in size, so the calculations are slightly off: pre-13 was 16 bytes each (20 when 64-bit compiled), and post-13 it is 6.32 bytes/heap tuple when deduplication has kicked in.