@Paul Janda
Paul, this was added to ASH in 11g as in 10g it wasn’t possible to determine from ASH data only whether a query was so active because it took so long time to execute or it was just executed so frequently. I don’t know whether any of the GUI tools actually used it or not … The SQL Monitoring report does show only the sql_exec_id of the monitored SQL…
It wraps to 0 when you hit 2^24 – 1, but that should be fine as the sql_exec_id should be used with the sql_exec_start column (date), so your old executions with similar sql_exec_ids would have different start date…