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From Apache Wiki <wikidi...@apache.org>
Subject [Hadoop Wiki] Update of "Hive/LanguageManual/LateralView" by PaulYang
Date Tue, 05 Jan 2010 01:13:29 GMT
Dear Wiki user,

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The "Hive/LanguageManual/LateralView" page has been changed by PaulYang.
http://wiki.apache.org/hadoop/Hive/LanguageManual/LateralView?action=diff&rev1=1&rev2=2

--------------------------------------------------

  
  == Description ==
  
- Lateral view is used in conjunction with user-defined table generating functions such as
explode(). As mentioned in [wiki:Self:Hive/LanguageManual/UDF#UDTF], a UDTF generates one
or more rows for each input row. A lateral view constructs a virtual table by applying the
UDTF to each row of base table and using the resulting output rows to form a virtual table
having the supplied table alias. In addition, each input row from the base table is joined
with the respective output rows in the virtual table.
+ Lateral view is used in conjunction with user-defined table generating functions such as
explode(). As mentioned in [wiki:Self:Hive/LanguageManual/UDF#UDTF], a UDTF generates one
or more output rows for each input row. A lateral view constructs a virtual table by applying
the UDTF to each row of base table and using the resulting output rows to form a virtual table
having the supplied table alias. In addition, each input row from the base table is joined
with the respective output rows in the virtual table.
  
  == Example ==
  
@@ -27, +27 @@

  
  and the user would like to count the total number of times an ad appears across all pages.
  
- A lateral view with explode() can be used to convert adid_list into separate rows using
the query:
+ A lateral view with explode() [wiki:Self:Hive/LanguageManual/UDF#explode] can be used to
convert adid_list into separate rows using the query:
  {{{
  SELECT pageid, adid FROM pageAds LATERAL VIEW explode(adid_list) adTable AS adid;
  }}}

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