FW: Oracle ?

I just wanted to find a couple of people who come from an Informix background like me, but also know Oracle. I just completed the Oracle Fundamentals I course, but still have some questions that the instructor couldn't answer. I think the specialise in their specific course, and the Fundamentals guy couldn't answer my performance tuning questions. One of my biggest questions - why does every Oracle dba I speak to, say that fragmentation of tables / too many extents (non-contiguous space) does not matter. Surely that should still matter, no matter which database you use ? Another big question - why does Oracle say that cooked space should be used rather than raw space - and this answer I got from their performance tuning guy as well. Dirk -----Original Message----- From: Art S. Kagel [mailto:KAGEL@bloomberg.net] Sent: Tuesday, December 14, 2004 5:34 PM To: Dirk Moolman Subject: Re: Oracle ? Dirk Moolman wrote: > Is there anyone on this group that also works with Oracle ? A little, but no recently. But there are others. What's up? Art S. Kagel > Dirk Moolman > Database and Unix Administrator > MXGROUP sending to informix-list

> One of my biggest questions - why does every Oracle dba I speak to, say > that fragmentation of tables / too many extents (non-contiguous space) > does not matter. Surely that should still matter, no matter which > database you use ? Nobody is saying that fragmentation is not an issue. Just that ALL types of fragmentation is in itself not an issue, and that any 'toxic' fragmenation is basically a sign of bad housekeeping and can largely be avoided by configuring an environment correctly See http://www.oracle.com/technology/deploy/availability/pdf/defrag.pdf Note that the best practice recommendations in this paper were targeted at Oracle7 and required manual configuration. They have now all been largely implemented as automatic capabilities in later releases > Another big question - why does Oracle say that cooked space should be > used rather than raw space - and this answer I got from their > performance tuning guy as well. > I think the argument goes that the percieved performance benefits of raw are minimal and mitigated by the manageability challenges for backup etc. Plenty of Oracle sites do use raw however. In fact, the real recommendation is somewhere between both. See http://www.oracle.com/technology/deploy/availability/pdf/oow2000_same.pdf Note that the best practice recommendations in this paper were automated in Oracle Database 10g with automatic storage management (ASM) - which also alleviates the need for a cluster volume manager if you are setting up these types of environments.