UNDO RETENTION GUARANTEE
304623Jun 25 2004 — edited May 23 2008I recently read in a recent article http://otn.oracle.com/pub/articles/10gdba/index.html about UNDO RETENTION GUARANTEE, I'm somewhat sceptical about this functionality and whilst the article shows how to configure this option, it fails to describe how oracle performs the function to "GUARANTEE" this elimiation of the ORA-01555 error.
Is it as follows, or something else?
a). Automatically extend the underying UNDO datafiles when required. Thereby potentially filling a file system and genreating a "device out of space error" rather than an ORA-01555 error
b). Or suspends DB activity, such happens if the Archive Destination fills, until additional UNDO space becomes available.
Can somebody please expand on this RETENTION GUARANTEE please. Because even though these options may elimate ORA-01555's, they are effectively just diverting the error elsewhere.
Thank you,