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RE: having multiple datafiles per tablespace vs. one datafile per

From: <ddorr.cs_at_clearstream.com>
Date: Fri, 15 Sep 2000 15:52:18 +0200
Message-Id: <10620.117102@fatcity.com>


> ----------
> From: Steve Adams[SMTP:steve.adams_at_ixora.com.au]
> Reply To: ORACLE-L_at_fatcity.com
> Sent: Friday, September 15, 2000 16:30
> To: Multiple recipients of list ORACLE-L
> Subject: RE: having multiple datafiles per tablespace vs. one
> datafile per tablespace
>
> Hi Babu,
>
> The potential drawbacks of having multiple datafiles are trivial compared
> to the
> potential benefits.
>
> On most platforms when you issue a CREATE TABLESPACE command with multiple
> datafiles, those datafiles will be "zeroed" in parallel by slave threads.
> Even
> on platforms that do not support this, you can do multiple ALTER
> TABLESPACE ADD
> DATAFILE commands in parallel.

        Hummm : I was under the impression ( not to say I was almost sure ) after some testing that if you have an ALTER TABLESPACE ADD DATAFILE running in one session, and you perform another one elsewhere, it will wait for the first one to complete before starting ...

        The workaround was to add small datafiles, and then resize them, which could be done in parallel.

        But I may be wrong ..... as it often happens :-)

> Therefore multiple datafiles can make tablespace
> creation much faster.
>
> For file system based databases, having multiple datafiles may reduce the
> risk
> of contention for the operating system's datafile read/write locks (inode
> locks).
>
> Having multiple datafiles per tablespace facilitates the adoption of a
> uniform
> datafile size policy, which in turn facilitates disk load rebalancing.
>
> Finally, I answered a related question on Ixora Answers a few weeks ago,
> and you
> may find that answer relevant. Look for the answer headed "Is AUTOEXTEND
> OK?" at
> http://www.ixora.com.au/q+a/0008/30150113.htm.
>
> @ Regards,
> @ Steve Adams
> @ http://www.ixora.com.au/
> @ http://www.christianity.net.au/
> @
> @ Going to OpenWorld?
> @ Catch the Ixora performance tuning seminar too!
> @ See http://www.ixora.com.au/seminars/ for details.
>
>
> -----Original Message-----
> [mailto:babu.nagarajan_at_iflexsolutions.com]
> Sent: Friday, 15 September 2000 22:20
> To: ORACLE-L_at_fatcity.com; oracledba_at_lazydba.com
> tablespace
>
>
> Hi
>
> Could any one point out the advantages/disadvantages of having multiple
> datafiles for a tablespace as against having one datafile per tablespace?
>
> --
> Author: Steve Adams
> INET: steve.adams_at_ixora.com.au
>
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Received on Fri Sep 15 2000 - 08:52:18 CDT

Original text of this message

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