Re: Are rowids unique among tables?

From: <oratune_at_aol.com>
Date: Fri, 06 Oct 2000 15:31:02 GMT
Message-ID: <8rkr7m$d0b$1@nnrp1.deja.com>

In article <8rkosm$b08$1_at_nnrp1.deja.com>,   oratune_at_aol.com wrote:
> In article <%8lD5.20828$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.

>

I neglected to qualify my last statement -- each and every ROWID is unique within a database outside of clusters, where two or more rows can occupy the same physical space.

--
David Fitzjarrell
Oracle Certified DBA


Sent via Deja.com http://www.deja.com/
Before you buy.

Received on Fri Oct 06 2000 - 10:31:02 CDT