On Wed, Nov 24, 2021 at 9:51 AM Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:
> On 2021-Nov-24, Robert Haas wrote:
> > Hmm. I think in my model an item and an item pointer and a line
> > pointer are all the same thing, but a TID is different. When I talk
> > about a TID, I mean the location of an item pointer, not its contents.
> > So a TID is what tells me that I want block 5 and the 4th slot in the
> > item pointer array. The item pointer tells me that the associate tuple
> > is at a certain position in the page and has a certain length.
>
> OK, but you can have item pointers that don't have any item.
> LP_REDIRECT, LP_DEAD, LP_UNUSED item pointers don't have items.
I guess so. I said before that I thought an item and an item pointer
were the same, but on reflection, that doesn't entirely make sense.
But I don't know that I like making item and tuple synonymous either.
I think perhaps the term "item" by itself is not very clear.
--
Robert Haas
EDB: http://www.enterprisedb.com