1) rollback segment will
not shrink.
Correct, assuming you do not shrink it manually.
2) It will keep growing till
tablespace fills up.
Correct assuming that you have a SQL statement that causes the rollback
segment to grow in such a way and that you have no constraints on the rollback
segments to prevent unconstrained growth (e.g. maxextents). Note that this may
not be a good thing... if you have one transaction that causes one rbs to grow
really large, that may prevent growth of other rbs's. Unless you are manually
assigning rollback segments to every transaction, that could have negative
consequences.
It is,
IMHO, best to have use automated undo, if possible, then you don't need to worry
about these things. If you can't use automated undo, then create a nice big
tablespace, but also use optimal, setting it to a reasonable
size.
3) And there will be no
'snapshot too old' errors?
Wrong.
Even with large rollback segments, 1555's are possible depending on a number of
things.
Robert G. Freeman
Technical Management Consultant
TUSC -
The Oracle Experts www.tusc.com
630.819.9077
Cell (It's everywhere that I am!)
Author of
several books you can find on Amazon.com!
-----Original Message-----
From: A Joshi [mailto:[EMAIL PROTECTED]
Sent: Sunday, December 28, 2003 12:39 AM
To: Multiple recipients of list ORACLE-L
Subject: Re: ** can two processes use the same rollback extentHi,A simple rollback segment question. If I do not set a optimal then can I assume following1) rollback segment will not shrink.2) It will keep growing till tablespace fills up.3) And there will be no 'snapshot too old' errors?Thanks
A Joshi <[EMAIL PROTECTED]> wrote:Hi,
One rollback segment can be used by multiple transactions/processes but what about the extents? Is it safe to assume that only one transaction/process can use one extent? What is a good way to size the extent for warehousing tasks? Or guess the rollback generated and size needed.
Thank You
Do you Yahoo!?
Protect your identity with Yahoo! Mail AddressGuard
Do you Yahoo!?
Protect your identity with Yahoo! Mail AddressGuard
