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https://issues.apache.org/jira/browse/CASSANDRA-9767?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14620583#comment-14620583
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Ajay edited comment on CASSANDRA-9767 at 7/9/15 2:33 PM:
---------------------------------------------------------
Yes the perfect example could have been GROUP BY. But I was trying to give an
example within a single partition. But the idea is the same. Now with aggregate
functions in 2.2, the CQL is supporting pulling columns along with other
aggregate functions (As I see from the samples). So it should work for COUNT
(*) as well.
was (Author: ajaygarga):
Yes the perfect example could have been GROUP BY. But I was trying to give an
example within a single partition. But the idea is the same. Now with aggregate
functions in 2.2, the CQL is supporting pulling columns along with other
aggregate functions (from the sample I noticed). So it should work for COUNT
(*) as well.
> Allow the selection of columns together with aggregates
> -------------------------------------------------------
>
> Key: CASSANDRA-9767
> URL: https://issues.apache.org/jira/browse/CASSANDRA-9767
> Project: Cassandra
> Issue Type: Wish
> Components: Core
> Environment: Cassandra 2.0.16
> Ubuntu 15.04
> Reporter: Ajay
> Assignee: Benjamin Lerer
> Priority: Minor
>
> Lets assume we have a column family as below:
> create table sample ( track_id int, user_id int, country varchar, primary key
> ((track_id), user_id));
> where track_id is the partition key.
> Now to aggregate the number of rows for a single track_id, we can query using
> CQL as below:
> select count(*) where track_id = 1 and user_id = 1;
> But that will return only the count. If we need the other columns along with
> the count, we cannot query as below as it throws error:
> select count(*), country from sample where track_id = 1 and user_id = 1;
> Bad Request: line 1:15 mismatched input ',' expecting K_FROM.
> In this case, all rows for a given track_id and user_id will have the same
> value for country. So we should be able to query as above. Also in SQL, it
> is possible to select columns along with aggregate functions.
> Though I know that Cassandra is not analytics (unlike Hadoop and Spark), we
> need some basic aggregate functions like min, max, avg etc....Though
> performance wise it might not be efficient, but it is better done in the
> cassandra side (as it uses native protocol) than we getting all rows in the
> client and doing the basic aggregation. It cannot used just as a data store
> (as garbage-in garbage-out). In that context, currently CQL is pretty
> limited. Just for getting data out of cassandra, we will have to spark though
> we will not be doing much analytics on it.
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