Query running slow

Hi List,

        The below query is taking a very long time to execute. The META_ROUTING table has around 19,95,347 records. How do I make the query run fast?

select /*+ use_hash(meta_routing)*/ meta_routing_key, org_stn_key, dest_stn_key, priority from meta_routing where priority in
(select min(priority) from meta_routing group by org_stn_key, dest_stn_key)
and (org_stn_key, dest_stn_key) not in(select org_stn_key, dest_stn_key from
(select dense_rank() over(partition by org_stn_key, dest_stn_key order by
priority nulls last) as ranking,
meta_routing_key, org_stn_key, dest_stn_key, priority from meta_routing)
where ranking = 2 )
union
select meta_routing_key, org_stn_key, dest_stn_key, priority from
(select dense_rank() over(partition by org_stn_key, dest_stn_key order by
priority nulls last) as ranking,
meta_routing_key, org_stn_key, dest_stn_key, priority from meta_routing)
where ranking = 2

Any help in this regard is very much appreciated.

Thanks and Regards,

Ranganath                                             

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Author: Krishnaswamy, Ranganath
  INET: Ranganath.Krishnaswamy_at_blr.hpsglobal.com

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