cassandra-commits mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Aleksey Yeschenko (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-4914) Aggregate functions in CQL
Date Mon, 23 Dec 2013 12:19:00 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-4914?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13855583#comment-13855583
] 

Aleksey Yeschenko commented on CASSANDRA-4914:
----------------------------------------------

bq. In the case of Cassandra, however, one mayor concern would be that for partitionable functions
like sum, count, min or max, each node could do its part of aggregation. For non-partitionable
function like average or percentiles, all the aggregation must be done at the coordinator.


This is not true at any RF > 1. The coordinator has to reconcile the partitions before
doing any kind of aggregation on them.

> Aggregate functions in CQL
> --------------------------
>
>                 Key: CASSANDRA-4914
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-4914
>             Project: Cassandra
>          Issue Type: New Feature
>            Reporter: Vijay
>            Assignee: Vijay
>             Fix For: 2.1
>
>
> 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



--
This message was sent by Atlassian JIRA
(v6.1.5#6160)

Mime
View raw message