Grokbase Groups Hive user July 2009
FAQ
The documentation appears to state the following:

"Multiple aggregations can be done at the same time, however, no two aggregations can have different DISTINCT columns .e.g while the following is possible "

" INSERT OVERWRITE TABLE pv_gender_agg
SELECT pv_users.gender, count(DISTINCT pv_users.userid), count(1), sum(DISTINCT pv_users.userid)
FROM pv_users
GROUP BY pv_users.gender;
However, the following query is not allowed. We don't allow multiple DISTINCT expressions in the same query.

INSERT OVERWRITE TABLE pv_gender_agg
SELECT pv_users.gender, count(DISTINCT pv_users.userid), count(DISTINCT pv_users.ip)
FROM pv_users
GROUP BY pv_users.gender;"


http://wiki.apache.org/hadoop/Hive/LanguageManual/GroupBy


Is there an effort underway to allow multiple DISTINCT expressions in the same query in the (near) future as well?

Thanks & regards,
Avram




-----Original Message-----
From: Amr Awadallah
Sent: Saturday, July 04, 2009 12:02 AM
To: hive-user@hadoop.apache.org
Subject: Re: aggregations over multiple columns?

Mike,

This is a valid query, group by over multiple columns works in hive.

-- amr

Michael E. Driscoll wrote:
Hi HIVErs,

I'm trying to perform the following aggregation query in HIVE, which
finds the largest purchase for all combinations of customer and store:

SELECT customer, store, max(purchasePrice)
FROM transactions
GROUP BY customer, store

If aggregation over multiple columns is not currently supported, how
might I reformulate this to work in HIVE, possibly via a simpler
series of queries?

(I will post the exact error and reproducible code if it turns out
this query is valid).

regards,

Mike

b: www.dataspora.com/blog
t: www.twitter.com/dataspora

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