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Oracle Tips by Burleson |
OCP Instructors Guide for
Oracle DBA Certification
Chapter 5 - Oracle Database
Objects
Rollback Segments and Users – Who’s Using
What?
The output from the query below will tell you
what rollback segment a user is using. The output provides the
rollback segment name, Oracle account and operating system account.
This is a good statement to use when an active transaction is
preventing a rollback segment from being taken offline or shrinking
back to its optimal size.
select osuser o, username u, segment_name s,
substr(sa.sql_text,1,200) txt
from v$session s, v$transaction t,
dba_rollback_segs r, v$sqlarea sa
SEE
CODE DEPOT FOR FULL SCRIPT
The statement provides the OS user account,
Oracle account, the rollback (or undo) segment name and the
statement that is currently executing.
Oracle9i - Database
Managed Undo Segments
You don’t have to be an Oracle expert to know
that rollback segments can be "somewhat troublesome." Out of space
conditions, contention, poor performance and the perennial favorite
"snap shot too old" errors have been plaguing Oracle database
administrators for over a decade. Oracle finally decided that the
database could probably do a better job of managing before images of
data than we could.
The above text is
an excerpt from:
OCP Instructors Guide for Oracle DBA Certification
A Study Guide to Advanced Oracle Certified Professional Database
Administration Techniques
ISBN 0-9744355-3-8
by Christopher T. Foot
http://www.rampant-books.com/book_2003_2_OCP_print.htm
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