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Date: Tue, 24 Mar 2009 12:47:50 -0700 (PDT)
From: "Raghotham Murthy (JIRA)" <jira@apache.org>
To: hive-dev@hadoop.apache.org
Subject: [jira] Issue Comment Edited: (HIVE-362) avg() returns null if any
 item in the list is null; create function that doesn't
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    [ https://issues.apache.org/jira/browse/HIVE-362?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12688827#action_12688827 ] 

Raghotham Murthy edited comment on HIVE-362 at 3/24/09 12:47 PM:
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In your example, even with NULLs, SUM(a) / COUNT(a) will be the same as AVG(a). This is because COUNT(a) returns the number of rows which have non-null 'a'. This is different from COUNT(1) which returns the count of all rows.

      was (Author: rsm):
    In your example, even with NULLs, SUM(a) / COUNT(a) will be the same as AVG(a). This is because COUNT(a) returns the number of rows which have non-null 'a'. This is different from COUNT(*) which returns the count of all rows.
  
> avg() returns null if any item in the list is null; create function that doesn't
> --------------------------------------------------------------------------------
>
>                 Key: HIVE-362
>                 URL: https://issues.apache.org/jira/browse/HIVE-362
>             Project: Hadoop Hive
>          Issue Type: Bug
>          Components: Query Processor
>            Reporter: Adam Kramer
>
> Some of the current aggregates (sum, avg) have a fairly standard behavior: If any item in the list is NULL, the sum, average, etc., cannot be computed. And so, NULL is returned.
> 1) If this is the case, the query should return much faster--see a null, return NULL, exit(0).
> 2) It would be nice to have versions or ways to use these functions with NULL data--specifically, to treat the NULL as zero or to ignore the NULL and return the results for non-NULL data.
> This also would apply to the variance functions referenced in https://issues.apache.org/jira/browse/HIVE-165

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