Oh brother....
Ok, assuming you have a single read/write arm and one read/write head (which is the
usual case), the arm has to go to the index location, read it, then go to the table
location and read that. If you perform several reads, it's going to go back and forth
between the index location and the table location. Having them on separate disks, and
hence separate read/write heads minimizes the back and forth movement, because on head
stays around the index, the other stays around the table. This movement, BTW, is
quite time consuming, relatively speaking.
>>> [EMAIL PROTECTED] 03/13/01 10:31AM >>>
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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