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https://issues.apache.org/jira/browse/CASSANDRA-10707?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15109181#comment-15109181
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Brian Hess commented on CASSANDRA-10707:
-----------------------------------------
Correct, what [~iamaleksey] said. In fact, pushing the aggregate computation
to the replicas is troublesome at an RF>1.
Quick follow up - will this ticket also cover:
SELECT clusterCol, Max(x) FROM myData GROUP BY clusterCol;
That is, you group on a clustering column, but not on a partition key?
Second question - consider a table with schema myData(partitionKey INT,
clusteringCol1 INT, clusteringCol2 INT, x INT, PRIMARY KEY ((partitionKey),
clusteringCol1, clusteringCol2). Now, will the following query be supported:
SELECT partitionKey, clusteringCol2, Sum(x) FROM myData GROUP BY partitionKey,
clusteringCol2;
The reason I ask is that the following is not supported:
SELECT partitionKey, clusteringCol2, x FROM myData WHERE partitionKey=5 ORDER
BY clusteringCol2;
Because you cannot order by clusteringCol2, only clusteringCol1.
> 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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