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

From: Diana Duncan <>
Date: Fri, 15 Sep 2000 15:03:51 -0400
Message-Id: <>

Steve (and others),

Is there a recommendation for the maximum number of datafiles that make sense for a database? We are expecting over 4000 (each account gets their own data and index tablespaces, each with one datafile apiece -- believe me, there are reasons for this), and that number may go higher. I'm starting to get concerned about the number, but I don't know if my concern is justified, or if I'm just paranoid.

Thanks for any input,

-----Original Message-----
From: Steve Adams [] Sent: Friday, September 15, 2000 10:31 AM 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. 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

@ Regards,
@ Steve Adams


@ Going to OpenWorld?
@ Catch the Ixora performance tuning seminar too!
@ See for details.

-----Original Message-----
[] Sent: Friday, 15 September 2000 22:20
To:; tablespace


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

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Received on Fri Sep 15 2000 - 14:03:51 CDT

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