AWR Interval discussion

A few weeks ago I shared several posts from Doug Burns about incremental global stats, and today are several posts from Doug on AWR Internal here and here.  Why am I suddenly thinking about this subject?  Well I keep an eye on our alert which monitors ASH data every hour as I've said many, many times before and this is absolutely a good discussion about what tools are useful when (especially if you read the comments of the first AWR post from Doug).