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Hive, mail # user - Re: Need rank()


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Re: Need rank()
Keith Wiley 2013-04-02, 17:03
On Apr 1, 2013, at 16:12 , Alexander Pivovarov wrote:

> http://ragrawal.wordpress.com/2011/11/18/extract-top-n-records-in-each-group-in-hadoophive/

Is there any possibility there is a bug in Ritesh Agrawal's query statement from that article?  I created a test table with the exact column names from the example in the article and used a minimally altered version of the command (I removed the where clause to simplify things a bit) and got an error which suggests there is something slightly wrong with the command (or perhaps the table has to be configured a special way).  Here's what I get when I almost perfectly duplicate that example:

hive> describe test;
OK
user string
category string
value int
Time taken: 0.082 seconds
=================================================hive> select * from test;
OK
user1 cat1 1
user1 cat1 2
user1 cat1 3
user1 cat2 10
user1 cat2 20
user1 cat2 30
user2 cat1 11
user2 cat1 21
user2 cat1 31
user2 cat2 5
user2 cat2 6
user2 cat2 7
Time taken: 0.202 seconds
=================================================hive> SELECT user, category, value
    > FROM (
    > SELECT user, category, rank(user) as rank, value
    > FROM test
    > DISTRIBUTE BY user
    > SORT BY user, value desc
    > ) a
    > WHERE rank > 1
    > ORDER BY user, rank;
FAILED: Error in semantic analysis: Line 9:15 Invalid table alias or column reference 'rank': (possible column names are: _col0, _col1, _col2)
hive>

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Keith Wiley     [EMAIL PROTECTED]     keithwiley.com    music.keithwiley.com

"What I primarily learned in grad school is how much I *don't* know.
Consequently, I left grad school with a higher ignorance to knowledge ratio than
when I entered."
                                           --  Keith Wiley
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