Re: Undo Management

A very strong caveat...the Oracle documentation on UNDO is less than accurate. Some of it is wrong, some of it is worded in a misleading way.

The basics of undo are the same. There are changes to the internal structures to accomodate the new space management algorithm, but it does not impact the actual undo. I wrote an indepth paper "Automatic Undo Internals" that you can download from www.evdbt.com. The first few and last few pages are probably what you are looking for (the middle few are a bunch of block dumps).

You can't just drop the undofile (I presume you mean datafile associated with the undo tablespace). In order to identify why the process is getting the ORA-01555, follow the same steps as you would with rollback segments, excluding things like dropping/creating/shrinking rollback segments, as this is not available when using AUM. Received on Thu Aug 25 2005 - 11:23:18 CDT