语句优化

写的一个导出查询 
CREATE OR REPLACE VIEW V_CREATE_KA_SELECTALL_EXPORT AS
select
               a.BASE_TYPE,
               a.AUTO_ID,
               a.TRADE_CODE_B,
               a.TRADE_NAME,
               a.COP_APP_NO,
               a.CAR_NO,
               a.STATUS,
               a.PORT_STATUS,
               wm_concat(';'|| '' || b.gatejob_no || '</br>' )as BILL_NO,
               a.SENDMARK,
               a.TSTYPE,
               a.YWTYPENEW,
               a.GATEJOB_NO_T,
               a.STATUS_NAME,
               a.PORT_STATUS_NAME,
               a.CREATEDATE,
               a.GDATETIME,
               a.YWTYPE,
               a.TYPE,
               a.YWTYPENAME,
               a.CAR_NUM,
               a.LAST_CAR,
               a.LASTNAME,
               a.FLAG1,
               a.FLAG2,
               a.TOTAL_WEIGHT,
               a.TOTAL_AMOUNT,
               a.ICCODE,
               a.F_CONTA_NO,
               a.F_CONTA_WT,
               a.A_CONTA_NO,
               a.A_CONTA_WT,
               a.CAR_J_WT,
               a.FROMKA,
               a.TOKA,
               a.FROMKA_NAME,
               a.TOKA_NAME,
               a.F_CONTA_TYPE,
               a.A_CONTA_TYPE,
               a.CAR_TYPE,
               a.DET_TYPE,
               a.REMARK2,
               a.TSTYPENAMES
          from V_CREATE_KA_SELECTALL a
          left join (SELECT Base_ID, GATEJOB_NO, GATEJOB_NO_REL
                      FROM CREATE_KA_JOB
                    UNION ALL
                    SELECT Base_ID, GATEJOB_NO, GATEJOB_NO_REL
                      FROM PORT_CREATE_KA_JOB) b
            on a.AUTO_ID = b.base_id
 group by a.BASE_TYPE,
               a.AUTO_ID,
               a.TRADE_CODE_B,
               a.TRADE_NAME,
               a.COP_APP_NO,
               a.CAR_NO,
               a.STATUS,
               a.PORT_STATUS,
               a.SENDMARK,
               a.TSTYPE,
               a.YWTYPENEW,
               a.GATEJOB_NO_T,
               a.STATUS_NAME,
               a.PORT_STATUS_NAME,
               a.CREATEDATE,
               a.GDATETIME,
               a.YWTYPE,
               a.TYPE,
               a.YWTYPENAME,
               a.CAR_NUM,
               a.LAST_CAR,
               a.LASTNAME,
               a.FLAG1,
               a.FLAG2,
               a.TOTAL_WEIGHT,
               a.TOTAL_AMOUNT,
               a.ICCODE,
               a.F_CONTA_NO,
               a.F_CONTA_WT,
               a.A_CONTA_NO,
               a.A_CONTA_WT,
               a.CAR_J_WT,
               a.FROMKA,
               a.TOKA,
               a.FROMKA_NAME,
               a.TOKA_NAME,
               a.F_CONTA_TYPE,
               a.A_CONTA_TYPE,
               a.CAR_TYPE,
               a.DET_TYPE,
               a.REMARK2,
               a.TSTYPENAMES;3-4万条数据还可以 查到8万条的时候 就很慢 占用内存很大了