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https://issues.apache.org/jira/browse/HIVE-287?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Arvind Prabhakar updated HIVE-287:
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Status: Patch Available (was: Open)
Fix Version/s: 0.6.0
*Summary*
This patch fixes the {{count()}} aggregate function to be consistent with SQL.
Specifically:
* Provides support for {{SELECT count(*) FROM table}} queries, where it returns
the total number of rows of the table.
* Also extended the support for {{count()}} to include multiple expression
list. {{count(DISTINCT expr1, exp2,...)}} returns the number of non-NULL and
different valued rows from the evaluated expressions.
*Details*
* Modified HiveQL grammar to allow function invocation with a single * in place
of parameter list.
* Propagated the presence of * as parameter or specification of {{DISTINCT}}
keyword in the UDF resolver framework so that it can be used by UDFs that
behave differently when these are applicable.
* Modified the {{count()}} UDAF to support the same semantics of handling NULL
values as regular SQL.
* Added test case to specifically exercise the newly introduced semantics of
the count UDAF.
*Testing*
Ran all tests. Noted only two failures (input20.q, input33.q) which were found
to be failing on the local trunk image as well.
If and when this patch is committed to the trunk, I will go ahead and update
the Hive Wiki with details and examples regarding the use of {{count()}} UDAF
in various forms.
> count distinct on multiple columns does not work
> ------------------------------------------------
>
> Key: HIVE-287
> URL: https://issues.apache.org/jira/browse/HIVE-287
> Project: Hadoop Hive
> Issue Type: Bug
> Components: Query Processor
> Reporter: Namit Jain
> Assignee: Arvind Prabhakar
> Fix For: 0.6.0
>
> Attachments: HIVE-287-1.patch
>
>
> The following query does not work:
> select count(distinct col1, col2) from Tbl
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