I don't believe you are correct. We are talking rowid not object_id.
Object_id is unique, but rowid is unique within a tablespace. Since The
realative file number is unique within a tablespace the file number is
assumed and not actually part of the rowid (it was in version 7). So they
made this change so they could have something like 1024 files in a
tablespace and 1024 tablespaces which together with the largest block size
etc. somehow gets you 50 petabytes. I remember this question coming up
during a beta training meeting at Oracle on Oracle 8. (I was with a company
that was a beta tester for Oracle 8 so we got a preview of the training with
the instructor's notes.)
Jim
<oratune_at_aol.com> wrote in message news:8rkosm$b08$1_at_nnrp1.deja.com...
> In article <%8lD5.20828$XV.1132383_at_nntp3.onemain.com>,
> "Barbara Kennedy" <barbken_at_teleport.com> wrote:
> > Actually in Oracle 8 rowid is unique within a tablespace. It is
possible to
> > have the same rowid in different tablespaces. This is a change from
Oracle
> > 7 and why the rowid changed. This is so they could have adatabase up
to a
> > total of 50 petabytes in size.
> > Jim
> > <pku12345_at_my-deja.com> wrote in message news:8rj6a2
$3nu$1_at_nnrp1.deja.com...
> > > By definition, a rowid identifies the storage location of a row
within
> > > a datafile/extent/block. Since no two rows (from the same table or
> > > otherwise) can physically occupy the same space, rowids are unique
> > > through out a given database. I don't know why your last query
didn't
> > > work though -- curious....
> > >
> > > Pei Ku
> > >
> > > In article <8rj4am$28m$1_at_nnrp1.deja.com>,
> > > kal121_at_my-deja.com wrote:
> > > > I know that rowids are unique within a given table, but are they
unique
> > > > among tables? I tried to verify this myself, but Oracle wouldn't
let
me.
> > > >
> > > > (works ok)
> > > >
> > > > SQL> select rowid from tab1;
> > > >
> > > > ROWID
> > > > ------------------
> > > > AAAA5bAAHAAAAFrAAA
> > > > AAAA5bAAHAAAAFrAAB
> > > >
> > > > (does not work)
> > > >
> > > > SQL> select rowid from tab1 where rowid in (select rowid from
tab2);
> > > >
> > > > select rowid from tab1 where rowid in (select rowid from tab2)
> > > > *
> > > > ERROR at line 1:
> > > > ORA-01410: invalid ROWID
> > > >
> > > > Sent via Deja.com http://www.deja.com/
> > > > Before you buy.
> > > >
> > >
> > >
> > > Sent via Deja.com http://www.deja.com/
> > > Before you buy.
> >
> >
>
> Unfortunately that is not quite correct; the relative file number is
> unique within a tablespace so the relative file number can be
> duplicated throughout a database between tablespaces, however the
> object_id (data object number in the extended rowid) is unique
> throughout the database, thus making each and every ROWID unique
> throughout.
>
> --
> David Fitzjarrell
> Oracle Certified DBA
>
>
> Sent via Deja.com http://www.deja.com/
> Before you buy.
Received on Fri Oct 06 2000 - 21:58:59 CDT
