RE: Tables and indexes on different disks

From: Koivu, Lisa <lkoivu_at_qode.com>
Date: Tue, 13 Mar 2001 09:17:23 -0800
Message-ID: <F001.002CB081.20010313090102@fatcity.com>

Mike,

It becomes more of a problem with inserts/updates. If you update a column that is indexed, or insert a record, the table is updated and the index is updated simultaneously. If the table and index(es) are both on the same disk, you will see contention.

Of course there are "exceptions" to the rule. The one I am aware of is if your database resides on EMC disks. The underlying cache can minimize contention.

Lisa Rutland Koivu
Oracle Database Administrator
Qode.com
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-----Original Message-----

From: Michal Zaschke [mailto:zaschke_at_suas.cz] Sent: Tuesday, March 13, 2001 10:31 AM
To: Multiple recipients of list ORACLE-L Subject: Tables and indexes on different disks

Hi all,

I've read an interesting section in Oracle Docu (Tuning I/O):

---

Separating Tables and Indexes

It is not necessary to separate a frequently used table from its index. During the course of a transaction, the index is read first, and then the table is read. Because these I/Os occur sequentially, the table and index can be stored on the same disk without contention.
---

Why do you then recommend to separate tables and indexes to different disks?

Thanks
Mike

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Author: Michal Zaschke
  INET: zaschke_at_suas.cz


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Received on Tue Mar 13 2001 - 11:17:23 CST