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https://issues.apache.org/jira/browse/CASSANDRA-4914?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14324266#comment-14324266
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Anton Slutsky commented on CASSANDRA-4914:
------------------------------------------
Robert Stupp, you are absolutely right! Somehow, I forgot we are hashing!
This is cool. I'll look into the code more carefully, but if hash buckets are
narrow enough, maybe true random sampling can be assumed. If that's the case,
then this is not that difficult to do.
Also, please dont add distributed calculation facilities to Cassandra! :) It
will turn it into a poor-man's hadoop and either you guys will have to support
a real distributed processing system or everyone will be pissed off that
Map/Reduce on Cassandra doesnt work like it does on Hadoop :-)
> Aggregation functions in CQL
> ----------------------------
>
> Key: CASSANDRA-4914
> URL: https://issues.apache.org/jira/browse/CASSANDRA-4914
> Project: Cassandra
> Issue Type: New Feature
> Reporter: Vijay
> Assignee: Benjamin Lerer
> Labels: cql, docs
> Fix For: 3.0
>
> Attachments: CASSANDRA-4914-V2.txt, CASSANDRA-4914-V3.txt,
> CASSANDRA-4914-V4.txt, CASSANDRA-4914-V5.txt, CASSANDRA-4914.txt
>
>
> The requirement is to do aggregation of data in Cassandra (Wide row of column
> values of int, double, float etc).
> With some basic agree gate functions like AVG, SUM, Mean, Min, Max, etc (for
> the columns within a row).
> Example:
> SELECT * FROM emp WHERE empID IN (130) ORDER BY deptID DESC;
>
> empid | deptid | first_name | last_name | salary
> -------+--------+------------+-----------+--------
> 130 | 3 | joe | doe | 10.1
> 130 | 2 | joe | doe | 100
> 130 | 1 | joe | doe | 1e+03
>
> SELECT sum(salary), empid FROM emp WHERE empID IN (130);
>
> sum(salary) | empid
> -------------+--------
> 1110.1 | 130
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