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From: Apache Wiki <wikidiffs@apache.org>
To: Apache Wiki <wikidiffs@apache.org>
Date: Fri, 16 Apr 2010 19:15:17 -0000
Message-ID: <20100416191517.16036.55233@eos.apache.org>
Subject: 
 =?utf-8?q?=5BHadoop_Wiki=5D_Update_of_=22Hive/Tutorial=22_by_Ning_Zhang?=

Dear Wiki user,

You have subscribed to a wiki page or wiki category on "Hadoop Wiki" for ch=
ange notification.

The "Hive/Tutorial" page has been changed by Ning Zhang.
http://wiki.apache.org/hadoop/Hive/Tutorial?action=3Ddiff&rev1=3D21&rev2=3D=
22

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

    * An additional pvs.country column is added in the select statement. Th=
is is the corresponding input column for the dynamic partition column. Note=
 that you do not need to add an input column for the static partition colum=
n because its value is already known in the PARTITION clause. =

  =

  Semantics of the dynamic partition insert statement:
+   * When there are already non-empty partitions exists for the dynamic pa=
rtition columns, (e.g., country=3D'CA' exists under some ds root partition)=
, it will be overwritten if the dynamic partition insert saw the same value=
 (say 'CA') in the input data. This is in line with the 'insert overwrite' =
semantics. However, if the partition value 'CA' does not appear in the inpu=
t data, the existing partition will not be overwritten. =

    * Since a Hive partition corresponds to a directory in HDFS, the partit=
ion value has to conform to the HDFS path format (URI in Java). Any charact=
er having a special meaning in URI (e.g., '%', ':', '/', '#') will be escap=
ed with '%' followed by 2 bytes of its ASCII value.  =

    * If the input column is a type different than STRING, its value will b=
e first converted to STRING to be used to construct the HDFS path. =

    * If the input column value is NULL or empty string, the row will be pu=
t into a special partition, whose name is controlled by the hive parameter =
hive.exec.default.dynamic.partition.name. The default value is __HIVE_DEFAU=
LT_PARTITION__. Basically this partition will contain all "bad" rows whose =
value are not valid partition names. The caveat of this approach is that th=
e bad value will be lost and is replaced by __HIVE_DEFAULT_PARTITION__ if y=
ou select them Hive. JIRA HIVE-1309 is a solution to let user specify "bad =
file" to retain the input partition column values as well.