Re: Cluster table based on grand parent?

On Tue, Mar 28, 2023 at 6:06 PM Ron <ronljohnsonjr(at)gmail(dot)com> wrote:

> You can only get from parent to grandchild via child.id to
> grandchild.parent, so why not cluster grandchild on grandchild.parent?
>

Hi. I don't understand your question. Yes, of course, if I want all
grand-children of a given parent, I'll do for example:

select p.id, c.id, c.name, gc.*
from grandchild gc
join child c on gc.parent = c.id
join parent p on c.parent = p.id
where p.name = $1

But w/o clustering on a denormalized grandchild.grandparent FK column, as
Peter showed,
and cluster only on grandchild.parent, that's not going to access a mostly
continuous range
of pages to fetch those all grandchild rows for that one parent. But
probably 10 to 50 "row-clusters",
given the fan-out I mentioned earlier at the child-table level. Or am I
missing something?