Note in line
--
Regards
Jonathan Lewis
http://www.jlcomp.demon.co.uk
The Co-operative Oracle Users' FAQ
http://www.jlcomp.demon.co.uk/faq/ind_faq.html
April 2004 Iceland
June 2004 UK - Optimising Oracle Seminar
"Howard J. Rogers" <hjr_at_dizwell.com> wrote in message
news:405614d5$0$3957$afc38c87_at_news.optusnet.com.au...
>
>
> That has not been true since 8i, if memory serves. It definitely isn't
true
> in 9i.
>
> The algorithm now appears to be to fill one disk up first, and then move
on
> to the other. It is probably subtler than that, but it's not round robin.
>
> Proof?
>
> SQL> create tablespace test
> 2 datafile 'c:\oracle\ora92\lx92\test01.dbf' size 5m,
> 3 'c:\oracle\ora92\lx92\test02.dbf' size 5m;
>
Can I take a guess that you are defaulting to
a locally managed tablespace with system
managed allocation ? (I can never remember what
the defaults are, and what DBCA kicks you with
these days).
> Tablespace created.
>
> SQL> create table blah tablespace test
> 2 as select * from emp;
>
> Table created.
>
> SQL> alter table blah allocate extent;
>
> Table altered.
>
> SQL> /
>
> <Repeat several times>
>
> SQL> select file_id from dba_extents
> 2 where segment_name='BLAH';
>
> FILE_ID
> ----------
> 7
> 7
> 7
> 7
> 7
> 7
> 7
>
> 7 rows selected.
>
> This behaviour has always puzzled me, since I am fairly certain that in
8.0
> and before the extents really *were* distributed alternately between the
two
> datafiles (or round-robined in a multi-file tablespace).
>
If you are on autoallocate / system allocated extent sizes, then the
first 16 extents (i.e. 1M) go into the first file, after which you get
the round-robin. (Unless it has changed since I last tested it, which
was some time ago)
Received on Mon Mar 15 2004 - 17:25:38 CST
