Quick example on Oracle logmnr (Log Miner)

begin
dbms_logmnr.add_logfile(logfilename=>'+DATA/orcl/archivelog/2011_06_30/thread_1_seq_400.522.755203825',
options=>dbms_logmnr.new);
end;
/

begin
dbms_logmnr.start_logmnr(options=>dbms_logmnr.dict_from_online_catalog);
end;
/
select substr(sql_redo,0,100), count(*) from v$logmnr_contents
group by substr(sql_redo,0,100);

begin
dbms_logmnr.end_logmnr();
end;
/