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Home -> Community -> Usenet -> c.d.o.server -> Re: What's the meaning of ROWID?
A copy of this was sent to Martin Haltmayer <Martin_Haltmayer_at_KirchGruppe.de> (if that email address didn't require changing) On Tue, 03 Mar 1998 14:50:00 +0100, you wrote:
>How can you have twice the same combination of (FILE the row is in, BLOCK within
>the file the row is in, SLOT in the block the row is in)?
>
clusters...
SQL> CREATE CLUSTER personnel
2 ( department_number NUMBER(2) )
3 SIZE 512;
Cluster created.
SQL>
SQL> create index personnel_idx on cluster personnel;
Index created.
SQL>
SQL> CREATE TABLE demo_emp
2 (empno NUMBER PRIMARY KEY,
3 ename VARCHAR2(10) NOT NULL,
4 deptno NUMBER(2) NOT NULL )
5 CLUSTER personnel (deptno);
Table created.
SQL> SQL> SQL> CREATE TABLE demo_dept
Table created.
SQL>
SQL> insert into demo_dept values ( 10, 'ABC', 'DEF' );
1 row created.
SQL> insert into demo_emp values ( 1, 'Tom', 10 );
1 row created.
SQL>
SQL> select rowid from demo_dept;
ROWID
SQL> select rowid from demo_emp;
ROWID
>Martin Haltmayer
>
>Thomas Kyte wrote:
>>
>> A copy of this was sent to Jimmy <c6635500_at_comp.polyu.edu.hk>
>> (if that email address didn't require changing)
>> On Mon, 02 Mar 1998 12:38:54 -0800, you wrote:
>>
>> >Hello all,
>> >
>> > Could anyone tells me what is the meaning of rowid? Is rowid unique
>> >with each record in a table? Is the lastest record with the largest
>> >rowid in a table?
>> >
>> >Thanks,
>> >Jimmy
>>
>> A rowid in Oracle is a physical address of a row. In Oracle7, it is the
>>
>> - FILE the row is in
>> - BLOCK within the file the row is in
>> - SLOT in the block the row is in
>>
>> In Oracle8, the internal format of the rowid is still file/block/slot however
>> the file# is a relative file number (relative within a tablespace).
>>
>> Externally, in Oracle7, you can see the file/block/slot easily in the external
>> representation of the rowid
>>
>> SQL> select rowid from dual;
>> ROWID
>> ------------------
>> 0000033D.0000.0001
>>
>> In Oracle8, they added more data to the external representation of the rowid, so
>> that it is not as 'readable' (but they added the dbms_rowid package to extract
>> all of the useful information):
>>
>> SQL> select rowid from dual;
>> ROWID
>> ------------------
>> AAAACsAABAAAAGiAAA
>>
>> A rowid is unique within a table -- and only within a table. The same Oracle7
>> rowid (believe it or not) can appear within the same database more then once. A
>> rowid is assigned to a row when it is inserted and stays with that row until it
>> is deleted (so if you insert a row, remove the row from the DB and then
>> re-insert it, it will probably get a different rowid the second time).
>>
>>
>> Thomas Kyte
>> tkyte_at_us.oracle.com
>> Oracle Government
>> Herndon VA
>>
>> http://govt.us.oracle.com/ -- downloadable utilities
>>
>> ----------------------------------------------------------------------------
>> Opinions are mine and do not necessarily reflect those of Oracle Corporation
>>
>> Anti-Anti Spam Msg: if you want an answer emailed to you,
>> you have to make it easy to get email to you. Any bounced
>> email will be treated the same way i treat SPAM-- I delete it.
Thomas Kyte
tkyte_at_us.oracle.com
Oracle Government
Herndon VA
http://govt.us.oracle.com/ -- downloadable utilities
Anti-Anti Spam Msg: if you want an answer emailed to you, you have to make it easy to get email to you. Any bounced email will be treated the same way i treat SPAM-- I delete it. Received on Thu Mar 05 1998 - 00:00:00 CST
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