I needed to change the undo_retention parameter in a 10gR2 database. Unfortunately I forgot whether the parameter was in seconds or minutes, and I wanted to see what the default was. So I open up the docs, go into the Reference guide and get the info I need from the top few lines. I wanted to set undo_retention to some large value in order to use flashback. So I decided to read if they were any notes about setting this too large. I started reading the notes. I’ve read this in the past, so didn’t expect anything new. Then I read the following: “For fixed-size undo tablespaces, the system automatically tunes for the maximum possible undo” What? Fixed size undo vs autoextend undo ? That’s new!