I do not understand why anyone would full text index an entire database, since text indexing your primary and foreign key columns is not worthwhile and you can probably think of many other columns that should not be indexed.
It also makes a very dangerous security situation. Consider you spend a great deal of time setting permissions on each table, so data is only available to authorized users. Then somene adds full text indexing on all tables so the "protected" data now appears in everyone's search results. Permissions are gone. You need to be careful to select a index/search tools that preserves with permissions.
I went to a demo of Autonomy a few years ago. It looked very good and even worked with Oracle row level security. However, it cost $100,000 and up.
You could with a privileged user like system do something like this
select 'select '''||owner||'.'||table_name||'.'||column_name||''' , rowid from '||owner||'.'||table_name||' where '||column_name||'=''AAA'' union' from dba_tab_columns c where c.DATA_TYPE= 'VARCHAR2'
1. include other datatypes you wish to search for
2. Exclude users your not interested in
3. Paste the output into a .sql file
4. remove the last union
5. run it in sqlplus or whatever else you run sql scripts from
6. When run it will take a long time so you may wish to kick it off last thing at night. You may wish to split the query into smaller more manageable chunks.
You could make it more sophisticated and get it to do the primary key for each table but that is trickier.