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From "Benjamin Lerer (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-10707) Add support for Group By to Select statement
Date Fri, 04 Mar 2016 13:50:40 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-10707?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15179895#comment-15179895
] 

Benjamin Lerer commented on CASSANDRA-10707:
--------------------------------------------

||patch||utests||dtests||
|[trunk|https://github.com/apache/cassandra/compare/trunk...blerer:10707-trunk]|[trunk|http://cassci.datastax.com/view/Dev/view/blerer/job/blerer-10707-trunk-testall/]|[trunk|http://cassci.datastax.com/view/Dev/view/blerer/job/blerer-10707-trunk-dtest/]|

I have pushed new commits to handle the last review comments. 

The patch does not fix yet the problem of shortRead but the current implementation is definitely
broken. As {{countedInCurrentPartition()}} is not overridden the row count is used to compute
the number of rows to fetch but the limit is then set in term of groups.

I have to take something to properly investigate this problem.

{quote}In the news file, you have IN restrictions with only one element are now considered
as equality restrictions. What does that mean for the user?{quote}

Some queries which use to be rejected will suddenly get accepted like multipartitions-queries
with {{ORDER BY}} and paging.
Some error messages will also be slightly different. 

I removed the entry for now as I agree that it might not be fully relevant for the users.



> Add support for Group By to Select statement
> --------------------------------------------
>
>                 Key: CASSANDRA-10707
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-10707
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: CQL
>            Reporter: Benjamin Lerer
>            Assignee: Benjamin Lerer
>
> Now that Cassandra support aggregate functions, it makes sense to support {{GROUP BY}}
on the {{SELECT}} statements.
> It should be possible to group either at the partition level or at the clustering column
level.
> {code}
> SELECT partitionKey, max(value) FROM myTable GROUP BY partitionKey;
> SELECT partitionKey, clustering0, clustering1, max(value) FROM myTable GROUP BY partitionKey,
clustering0, clustering1; 
> {code}



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