我有一个Oracle查询，它在某些环境中偶尔使用执行速度非常慢的执行计划。
我可以采取哪些步骤来优化此查询，使其始终使用更快的执行计划？或者换句话说，是否有任何特定的领域特别低效或迂回？

select 
 'RECEIVE-DONE' OP_TYPE,   
 sbmt.SUBMIT_NO, 
 wsr.USE_LUMP_PROC, 
 sf.* 
from ( 
 select 
 my.flow_id myflow_id, 
 done.flow_id flow_id, 
 done.status SFSTATUS, 
 from submit_flow my , submit_flow done 
  where my.submit_id=done.submit_id 
  and my.check_ord=done.check_ord 
  and my.emp_id = '1'
  and done.status
  in (1,2,3,4) 
  and ( (done.mainflow=1 and done.check_ord > 0) or (done.emp_id ='1' and done.type in (1,2,3) and done.type = my.type ) )  
  ) sf,  
  submit_list sbmt, wfserveroute wsr, emp emp 
where  
 sbmt.EMP_ID = emp.EMP_ID 
 and sf.SUBMIT_ID = sbmt.SUBMIT_ID 
 and ((sf.TYPE = 1 and sbmt.COMPLETED = 1 and sbmt.status = 2) or (sf.TYPE <> 1)) 
 and sbmt.FLOW_SCHEM  = wsr.SCHEM   
 and sbmt.SERVICENAME = wsr.FULLNAME 
 and wsr.CASE = 0 
 and not exists( 
 SELECT 1 FROM service_mst smst 
 WHERE   (smst.namespace||'.'||smst.name) = sbmt.SERVICENAME
 and  smst.not_view_at_inouttray = 1  
 )  order by sf.prc_date DESC

我发现执行计划中的Table Access Full和Merge Join Cartesian的示例在速度方面不太理想，但我不确定为了鼓励使用不包括它们的计划，需要对SQL进行有形的修改。
应更新用于为有关表格制定计划的统计数据。