> If they are both accesed at the same time, it will improve performance or > not, > I don't understand exactly what is this myth about? From the perspective of a single query, the indexes are not accessed at the same time as the data. Take a look at a trace file to verify it if you like. From the perspective of many queries executing simultaneously, it still doesn't really matter. You have several queries access both data and indexes. There can be contention for either one. What matters is the performance of your system under load. If you have 10 disks in a RAID 0 with all indexes and data residing on it and the performance is somewhat lackluster, splitting those disks into two 5 disk RAID 0 drives and physically separating the indexes and data will not improve performance. It would be very likely though that it would decrease performance, particularly on full table scans and fast full index scans. Jared ---------------------------------------------------------------- Please see the official ORACLE-L FAQ: http://www.orafaq.com ---------------------------------------------------------------- To unsubscribe send email to: oracle-l-request@xxxxxxxxxxxxx put 'unsubscribe' in the subject line. -- Archives are at //www.freelists.org/archives/oracle-l/ FAQ is at //www.freelists.org/help/fom-serve/cache/1.html -----------------------------------------------------------------