Re: [HACKERS] Fwd: Joins and links

> Leon <leon@udmnet.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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