REPORT SCHEMA is quite handy to get growth rate of your database/datafile/tablespace providing RMAN repository is used. I don’t remember what triggered that thought but I see it in my “to blog” list so here it goes.

Running several times REPORT SCHEMA AT TIME 'SYSDATE-n'; and processing the results will provide nice trend with granularity up to datafile. It can be processed and aggregated to tablespace or the whole database.

I don’t see that historical datafile information is stored in a repository so RMAN, probably, calculates or implies it from data about backups taken (BDF table?). That means that timeline precision depends in the backups frequency. I’ve run REPORT SCHEMA AT TIME with DEBUG ON quickly but it shows only calls to RMAN internal package and I didn’t have enough time to trace the queries.