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Hive >> mail # user >> Re: Need rank()


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Keith Wiley 2013-04-02, 17:03
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Nitin Pawar 2013-04-02, 17:06
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Keith Wiley 2013-04-02, 17:15
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Nitin Pawar 2013-04-02, 17:22
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Keith Wiley 2013-04-02, 19:44
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Keith Wiley 2013-04-02, 19:48
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Igor Tatarinov 2013-04-02, 17:56
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Re: Need rank()
Yep, the original article is definitely erroneous in this regard.  I figured out that eventually.  I'm not sure how much I can trust that resource now.  I may have to look elsewhere.  I agree that Edward's description is pretty good, but as I said earlier, I can't actually use his code, so I'm trying to cobble a workable solution together from the various resources available.  Ritesh's article, despite the error in the Hive syntax, is still useful in that it enables one to quickly compile a simple rank jar without relying on git, maven, or other project dependencies -- problems which have plagued me with Edward's approach.  So, if I can use Ritesh's method to write a simple rank function, and Edward's accurate description of how to construct the query, then I can put all the pieces together into a workable solution.

I'll let you know if I get it.

On Apr 2, 2013, at 10:56 , Igor Tatarinov wrote:

> You are getting the error because you are ORDERing BY rank but rank is not in the top SELECT
>
> Also, DISTRIBUTE BY/SORT BY are done after SELECT so you have to use a subquery:
> SELECT ..., rank(user)
> FROM (SELECT ... DISTRIBUTE BY ... SORT BY)
>
> igor
> decide.com
>
>
> On Tue, Apr 2, 2013 at 10:03 AM, Keith Wiley <[EMAIL PROTECTED]> wrote:
> 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>
>
> ________________________________________________________________________________
> 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
> ________________________________________________________________________________
>
>
________________________________________________________________________________
Keith Wiley     [EMAIL PROTECTED]     keithwiley.com    music.keithwiley.com

"Luminous beings are we, not this crude matter."
                                           --  Yoda
________________________________________________________________________________
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Edward Capriolo 2013-04-02, 20:14
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Edward Capriolo 2013-04-02, 19:59
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Keith Wiley 2013-04-02, 20:44