*10053 event will help to check why CBO makes the decision* alter session set events '10053 trace name context forever, level 1'; SELECT LEGACY_VENDOR_NO FROM TXRIOH0_INV_OUTBOUND_HDRS_ALL WHERE LPAD(NVL(VOUCHER_NO,0),7,'0') = :B2 AND NVL(SYSTEM,1) = NVL(:B1 ,1) AND BATCH_STATUS NOT IN ('CONFIRMED','PAID','RECEIVED') alter session set events '10053 trace name context off'; *get the tracefile* col tracefile for A120 select value ||'/'||(select instance_name from v$instance) ||'_ora_'|| (select spid||case when traceid is not null then '_'||traceid else null end from v$process where addr = (select paddr from v$session where sid = (select sid from v$mystat where rownum = 1 ) ) ) || '.trc' tracefile from v$parameter where name = 'user_dump_dest'; -- Regards Sidney Chen -- //www.freelists.org/webpage/oracle-l