Re: Rename dead_tuples to dead_items in vacuumlazy.c - Mailing list pgsql-hackers

From Alvaro Herrera
Subject Re: Rename dead_tuples to dead_items in vacuumlazy.c
Date
Msg-id 202111241451.47dzrgdmsuyt@alvherre.pgsql
Whole thread Raw
In response to Re: Rename dead_tuples to dead_items in vacuumlazy.c  (Robert Haas <robertmhaas@gmail.com>)
Responses Re: Rename dead_tuples to dead_items in vacuumlazy.c
Re: Rename dead_tuples to dead_items in vacuumlazy.c
List pgsql-hackers
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.

-- 
Álvaro Herrera              Valdivia, Chile  —  https://www.EnterpriseDB.com/
"Nunca confiaré en un traidor.  Ni siquiera si el traidor lo he creado yo"
(Barón Vladimir Harkonnen)



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