Oracle FAQ Your Portal to the Oracle Knowledge Grid

Home -> Community -> Mailing Lists -> Oracle-L -> RE: should you seperate indexes from tables in seperate datafiles

RE: should you seperate indexes from tables in seperate datafiles

From: Mercadante, Thomas F <>
Date: Tue, 15 Jul 2003 10:08:41 -0400
Message-Id: <>


Some of it depends on the disk storage. I have always followed the time-proven method of organizing disks and placing indexes away from the tables they belong to.

Our warehouse is using EMC external disk. What the warehouse architect did was to stripe the EMC disks in such a way that all mount points (Sun system) are spread across all the EMC disks. What this does is to spread all files in the database across all the EMC drives. And with 4 Gig of EMC cache available, it further disproves the theory that separing indexes from data are required. The end result, in my case, is almost like one big RAM disk - where all disk IO is spread across all disk.

If you do not have this arrangement, then I would still try and keep indexes and data away from each other. But let's face it, we *never* have enough disk mount points, so we end up merging things together somewhat anyway.

hope this helps.

Tom Mercadante
Oracle Certified Professional

-----Original Message-----
From: [] Sent: Tuesday, July 15, 2003 10:49 AM
To: Multiple recipients of list ORACLE-L Subject: should you seperate indexes from tables in seperate datafiles?

There has been alot of literature stating that you will recieve performance improvements by seperating indexes and tables across multiple I/O points.

Ie... you have a tables tablespace and an index tablespace. If you put them on seperate hard drives, you will have less I/O contention.

Now Im seeing some articles stating that this is not true. That oracle actually accesses indexes and tables serially. Now it might be useful seperate indexes from tables for maintenance purposes but this wont lower I/O contention.

Can anyone chime in on this? Curious to see where the evidence is leading?


Please see the official ORACLE-L FAQ:

Author: <

Fat City Network Services    -- 858-538-5051
San Diego, California        -- Mailing list and web hosting services
To REMOVE yourself from this mailing list, send an E-Mail message to: (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). Received on Tue Jul 15 2003 - 09:08:41 CDT

Original text of this message