MVCC – the part of PostgreSQL we hate the most (2023)

This topic cannot be discussed alone without talking about disks. SSDs write 4k page at a time. Meaning if you're going to update 1 bit, the disk will read 4k, you update the bit, and it writes back a 4k page in a new slot. So the penalty for copying varies depending on the disk type.

Interesting! I wonder how this plays into AWS pricing. They charge a flat fate for MBps of IO. But I don’t know if they have a rule to round up to nearest 4K, or they actually charge you the IO amount from the storage implementation by tracking write volume on the drive itself, rather what you requested.