Hive nested query left join

Question

I'am new to hive and i want to implement the following query

   select a.controlid, 
          b.name as campaign, 
          a.controlactivityid as activitysource,
          c.code as  codemyaprc,
          c.label_en as label_en,
          c.label_fr as label_fr
   from bo_h_control.bridgeactivity a 
        join suvh_econtrol.TMP_GPS_REF b ON a.controlcampaignid = 
   b.ps_cam_id
        left join  srv_h_a8460_fpc.activity c 
                   ON a.controlactivityid=c.code 
                      and c.date_creation= select 
   max(date_creation) from srv_h_a8460_fpc.activity

It works fine untill the last left join. Nested queries are obviously not authorized in hive.

How can i approach this.

Answer 1

Use sub-query instead of joined table:

 select a.controlid, 
          b.name as campaign, 
          a.controlactivityid as activitysource,
          c.code as  codemyaprc,
          c.label_en as label_en,
          c.label_fr as label_fr
   from bo_h_control.bridgeactivity a 
        join suvh_econtrol.TMP_GPS_REF b ON a.controlcampaignid = 
   b.ps_cam_id
        left join (select c.*, max(date_creation) over() as max_date_creation
                     from srv_h_a8460_fpc.activity c 
                  ) c ON a.controlactivityid=c.code 
                         and c.date_creation=c.max_date_creation

Or better move last join condition inside the WHERE clause in the subquery:

 select a.controlid, 
          b.name as campaign, 
          a.controlactivityid as activitysource,
          c.code as  codemyaprc,
          c.label_en as label_en,
          c.label_fr as label_fr
   from bo_h_control.bridgeactivity a 
        join suvh_econtrol.TMP_GPS_REF b ON a.controlcampaignid = 
   b.ps_cam_id
        left join (select * from
                   (
                   select c.*, max(date_creation) over() as max_date_creation
                     from srv_h_a8460_fpc.activity c 
                   )c where max_date_creation=date_creation
                  ) c ON a.controlactivityid=c.code