> Some other databases have the notion of a ROWID which uniquely
identifies a row
> within a table. OID can be used for that, but it means if you use it,
you must
> limit the size of your whole database system.
Imho that is getting it all wrong. OID is *not* a suitable substitute
for other
db's ROWID.
If you take a few extra precautions then you can use XTID in PostgreSQL
instead of other's ROWID.
We often hear, that it is safer to use ROWID in Oracle and Informix than
in
PostgreSQL. It is only true that the risc of getting at the wrong record
is
lower. Are you going to take chances when manipulating rows ? NO !
Thus any sensible program working on ROWID's will have builtin
precautions,
like locking the table, or using additional where quals.
I am still of the opinion, that we should invent an alias ROWID at the
SQL level
for the current XTID. I do not think that it matters what datatype this
ROWID is,
an arbitrary string like xtid is sufficient, it does not need to be an
integer.
Andreas