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From "Tomas Salfischberger (JIRA)" <j...@apache.org>
Subject [jira] [Issue Comment Edited] (CASSANDRA-2830) Allow summing of counter columns in CQL
Date Mon, 27 Jun 2011 22:06:47 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-2830?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13055798#comment-13055798
] 

Tomas Salfischberger edited comment on CASSANDRA-2830 at 6/27/11 10:06 PM:
---------------------------------------------------------------------------

I did a really crude trial of adding the SUM keyword to the Cql.g definition and handle it
in the same way as COUNT is done. It works, I can SUM my counter columns using CQL, but this
is of course not a great way to implement it.

Any pointers for the right way to implement this? How do we want to define generic aggregate
functions in the grammar and what would be the best way to handle them?

      was (Author: t0mas):
    I did a really crude trail of adding the SUM keyword to the Cql.g definition and handle
it in the same way as COUNT is done. It works, I can SUM my counter columns using CQL, but
this is of course not a great way to implement it.

Any pointers for the right way to implement this? How do we want to define generic aggregate
functions in the grammar and what would be the best way to handle them?
  
> Allow summing of counter columns in CQL
> ---------------------------------------
>
>                 Key: CASSANDRA-2830
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-2830
>             Project: Cassandra
>          Issue Type: New Feature
>          Components: API
>            Reporter: Tomas Salfischberger
>            Priority: Minor
>              Labels: CQL
>
> CQL could be extended with a method to calculate the sum of a set of counter columns.
This avoids transferring a long list of counter columns to be summed by the client, while
the server could calculate the total and instead only transfer that result. My proposal for
the syntax (based on the COUNT() suggestion in the comments of CASSANDRA-1704):
> {code}SELECT SUM(<columnFrom>..<columnTo>) FROM <CF> WHERE ...{code}
> The simplest approach would be to only allow summing of counters under the same key,
thus a query with a WHERE part that specifies multiple keys would return 1 result per key.
This avoids summing values from different nodes.

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