Poul Jensen <flyvholm@gfy.ku.dk> writes:
> One thought: PostgreSQL adds to every table a system column tableoid
> containing a constant value. Is that value really stored 1,000 times for
> a 1,000-row table? Or...?
No, tableoid is sort of a virtual column ... it doesn't exist on disk.
When you query it you get a value fetched from the internal data
structure representing the table.
There is plenty of *real* overhead per row, mind you, but tableoid isn't
part of it. You can read some details here:
http://developer.postgresql.org/docs/postgres/storage-page-layout.html
regards, tom lane