oracle performance tuning

add a join_key=1 to both tables then join tables on that key and see the difference between Merge-sort vs Hash-join 

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      -- out 5,6

t1.join_key = t2.join_key 
AND ( (INSTR(t1.SERVICE_NUMBER, t2.SERVICE_DIGIT) > 0 AND INSTR(t1.SERVICE_PLATFORM, t2.SERVICE_PLATFORM) > 0)
/* ( t1.SERVICE_NUMBER    like '%' || t2.SERVICE_DIGIT || '%' and t1.SERVICE_PLATFORM  like '%' || t2.SERVICE_PLATFORM || '%')*/
      OR
      ( t1.SERVICE_VARIANT_ID= TO_CHAR(t2.SERVICE_VARIANT_ID )AND t1.SDPA_FLAG != 0 AND t1.ABONELIK_FLAG = 'N' ) ) 
AND  T1.DCALL_DATE BETWEEN t2.START_DATE(+) AND t2.END_DATE(+)