For good performance in oracle need tunning your database. Can use Build Index for the example :

Build Index :

BEGIN
  SYS.DBMS_STATS.GATHER_INDEX_STATS (
      OwnName        => 'DIARYCODING_DB'
     ,IndName        => 'DIARY_REASON_PK'
    ,Estimate_Percent  => 0
    ,Degree            => 4
    ,No_Invalidate     => FALSE);
END;

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