First day at IOUG. The opening session was an informative sneak peak at some of the new 11g features coming out. Probably all old hat to Christo, our Pythian 11g “expert”. He has been very active in the 11g Beta program.
I enjoyed Kirti Desphande’s session on Flashback Technologies. He did an excellent job covering many of the flashback features. One thing I want to check out is whether our UNDO tablespaces are autoextensible or not. Kirti described a bit in Oracle 10g release 2 (associated with the automatic undo retention tuning), where the database uses more UNDO in release 2 than release 1 if you are using fixed size files. The workaround is to set the files as autoextensibe but set the max size to the current size. Will have to check it out. Thanks Kirt.
I had a very large turnout for my session “Flash Recovery Area: Friend or Foe?”. The session was quite interactive, with lots of questions from the attendees. And gratefully, all of the live demos worked !!!
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“Kirti described a bit in Oracle 10g release 2 (associated with the automatic undo retention tuning), where the database uses more UNDO in release 2 than release 1 if you are using fixed size files.”
That is because undo_retention is ignored in 10GR2 for non-autoextend (unless you are in guarantee mode) mode. 10GR2 automatically tunes for maximum retention unless you are using autoextend=on.
Oracle just keep as much undo as it can regardless of the undo_retention. This is documented in 10GR2 manuals.