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Your opinion please...RBSWe have created large rb's (100mb) and placed them
into their own rbbig tablespace, but we use them for specific tasks.
Meaning, they are not online by default, however if we are going to be
running a large import or export, we will turn off all of the little ones
and bring these big ones online. Of course, we are a developement shop so
it is probably a lot different in a production environement.
kev
-----Original Message-----
From: root_at_fatcity.com [mailto:root_at_fatcity.com]On Behalf Of Koivu, Lisa
Sent: Tuesday, December 12, 2000 9:06 AM
To: Multiple recipients of list ORACLE-L
Subject: Your opinion please...RBS
Good morning -
I'm reading through some doco about rollback segments and refreshing my memory. I remember a list discussion in the past about 'what is the point of optimal' with rbs's. The book I am reading (Oracle8i DBA Handbook, Oracle Press) states that shrinking to optimal, and extending a rollback segment, are both costly.
Seems to me if you don't have the luxury of a very large tablespace then utilizing optimal is your only way to get rbs's to share disk nicely.
However, if extending and shrinking is that costly, and you have a ton of disk at your disposal, I wonder about making my rbs's fairly large. Optimal right now is 40M (seems large to me). Our main app is more of a hybrid system, so I see wild numbers in v$rollstat - HWM's from 40M to 300M+. Has anyone just created really large rollback segments based on these types of weird sizes?
I also see waits in v$rollstat, and undo waits in v$waitstat. I just bumped up the number of rbs's to 26 based upon a recent HWM of 101 concurrent sessions. My waits are still growing!! Is it totally wild of me to think about adding even more rbs's?? I have more disk than I could ever realistically use in my rbs ts (10G). I am thinking about just doubling the number of rbs's because 1. I don't want to see ANY rbs waits in v$rollstat, v$waitstat and 2. because I've got the disk.
Am I out in left field? Any comments, suggestions, swift KITA's are appreciated. Gracias
Lisa Rutland Koivu
*O*penly *C*ynical & *P*essimistic
Qode.com
4850 North State Road 7
Suite G104
Fort Lauderdale, FL 33319
V: 954.484.3191, x174 F: 954.484.2933 C: 954.658.5849
"The information contained herein does not express the opinion or position of Qode.com and cannot be attributed to or made binding upon Qode.com."
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Received on Tue Dec 12 2000 - 08:29:48 CST