[tomnipotent]

I believe they were just pointing out that Postgres doesn't do in-place updates, so every update (with or without partitions) is a write followed by marking the previous tuple deleted so it can get vacuumed.

[snuxoll]

That’s not at all what the child to me was saying in even a generous reading.

But HOT updates are a thing, too.

[tomnipotent]

What do you think they were saying? I don't see any other way to read it.

HOT updates write to the same tuple page and can avoid updating indexes, but it's still a write followed by marking the old tuple for deletion.