What can change ORA_ROWSCN except for DML statements?

Hi,

I manage a database schema where some tables' contents are modified periodically with some update procedures.

I wanted to check when the last change occurred for every table in the schema and used ORA_ROWSCN.

What I did was:

1. Find the maximum value of ORA_ROWSCN in the table.

2. Find the corresponding time instant with the function scn_to_timestamp.

I was surprised that I found recent changes also in tables that were not changed by the procedures. Moreover, repeating the test after about three hours

revealed that also the time of latest change moved forward.

There was no change in the record count, so I got suspicious that some UPDATEs were taking place there. So I wrote a trigger for one table trying to catch updates, but I didn't detect anything.