Re: [HACKERS] Fwd: Joins and links

> Leon <leon(at)udmnet(dot)ru> writes:
> > We should make a real reference in one table to another! That
> > means there could be special data type called, say, "link",
> > which is a physical record number in the foreign table.
>
> There is no such thing as a physical record number for a tuple in
> Postgres. The closest you could come is an OID, which isn't really any
> faster than any other joinable field --- you still need an index to
> support fast lookup by OID.

Actually, there is:

select ctid from pg_class;

ctid
------
(0,1)
(0,2)
...

The number is the block number offset in the block. It doesn't help
because UPDATED rows would get a new tid. Tid's can be used for short
periods if you are sure the data in the table doesn't change, and there
is a TODO item to allow ctid reference in the WHERE clause.

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