Record IDs

The DBMS needs a ways to keep track of individual tuples

Each tuple is assigned a unique record identifier.

-> Most common: page_id + offset/slot

An application cannot rely on these ids to mean anything

Postgres

ctid (page, slot): physical location of the data

Insert to the end

VACUUM FULL : like a garbage collector, it go through anh reorganize all the pages

SQL server

SELECT sys.fn_PhysLocFormatter (%%physloc%%) AS [File:Page:Slot], * FROM TEST;

Delete id 102:

Insert 104

Oracle

Has the rowid