TS free space – need fresh understanding

Oracle 12.1.0.2 SE2

Standalone ASM – no RAC, no clustering

Oracle Linux 6

I am starting to second-guess myself.  This is a DW application, so the db is mostly like the Roach Motel – data checks in but never checks out.

I have a query that runs daily to check when a TS is getting full and might need an additional data file.  Here is the query that drives the procedure:

select tablespace_name,       used_percentfrom DBA_TABLESPACE_USAGE_METRICSwhere used_percent > i_alert_pct  -- i_alert_pct is run-time input parameter, set at 90order by used_percent desc

I’ve been getting these alerts on one particular TS with increasing frequency.  So trying to get a handle on it, I run a variant of the above query: