Link to a very good article about how to use Log Miner

 Log Miner setup steps:

https://www.thegeekdiary.com/simple-steps-to-use-logminer-for-finding-high-redo-log-generation/

Just in case the link will move, the main steps are below:

SQL> EXECUTE DBMS_LOGMNR.ADD_LOGFILE('/u01/app/oracle/users/Florin/MYDB_1_714407_821540104.arc',OPTIONS => DBMS_LOGMNR.NEW);

PL/SQL procedure successfully completed.

SQL> EXECUTE DBMS_LOGMNR.ADD_LOGFILE('/u01/app/oracle/users/Florin/MYDB_1_714408_821540104.arc',OPTIONS => DBMS_LOGMNR.ADDFILE);

PL/SQL procedure successfully completed.

SQL> EXECUTE DBMS_LOGMNR.START_LOGMNR( -

     OPTIONS => DBMS_LOGMNR.DICT_FROM_ONLINE_CATALOG);>

PL/SQL procedure successfully completed.

SQL> l

  1  select USERNAME,OS_USERNAME,MACHINE_NAME,SESSION_INFO from V$LOGMNR_CONTENTS

  2  where TABLE_NAME='MY_TABLE'

  3  and OPERATION='DELETE'

  4* and rownum < 11

How to transfer a "good" execution plan from one DB to another?

 The article below is very good and useful, I was following the instructions and I was able to force the Production DB execution plan in ST DB, even that the problematic query never used the good plan in UAT.

https://docs.rackspace.com/blog/transfer-sql-plans-by-using-sql-plan-baseline/

Florin