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From Apache Wiki <wikidi...@apache.org>
Subject [Hadoop Wiki] Update of "Hive/Tutorial" by PeterSkomoroch
Date Mon, 15 Jun 2009 21:43:18 GMT
Dear Wiki user,

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The following page has been changed by PeterSkomoroch:
http://wiki.apache.org/hadoop/Hive/Tutorial

The comment on the change is:
fix union example, small equi-join edit

------------------------------------------------------------------------------
      WHERE pv.date = '2008-03-03';  
  }}}
  
- Note that in Hive only support equi-joins. In order to do outer joins the user can qualify
the join with LEFT OUTER, RIGHT OUTER or FULL OUTER keywords in order to indicate the kind
of outer join (left preserved, right preserved or both sides preserved). e.g. in order to
do a full outer join in the query above, the corresponding syntax would look like the following
query: 
+ In order to do outer joins the user can qualify the join with LEFT OUTER, RIGHT OUTER or
FULL OUTER keywords in order to indicate the kind of outer join (left preserved, right preserved
or both sides preserved). e.g. in order to do a full outer join in the query above, the corresponding
syntax would look like the following query: 
  {{{     
      INSERT OVERWRITE TABLE pv_users 
      SELECT pv.*, u.gender, u.age 
@@ -364, +364 @@

      WHERE pv.date = '2008-03-03'; 
  }}}
  
+ Note that Hive only supports [http://en.wikipedia.org/wiki/Join_(SQL)#Equi-join equi-joins].

+ 
  == Aggregations ==
  In order to count the number of distinct users by gender one could write the following query:

  
@@ -450, +452 @@

  
  {{{    
      INSERT OVERWRITE TABLE actions_users 
-     SELECT u.id, actions.date; 
+     SELECT u.id, actions.date
      FROM (
          SELECT av.uid AS uid 
          FROM action_video av 
@@ -461, +463 @@

          SELECT ac.uid AS uid 
          FROM action_comment ac 
          WHERE ac.date = '2008-06-03' 
-         ) actions JOIN users u ON(u.id = actions.uid) 
+         ) actions JOIN users u ON(u.id = actions.uid);
  }}}
  
  == Array Operations ==

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