Mailing-List: contact commits-help@cassandra.apache.org; run by ezmlm
Precedence: bulk
Reply-To: dev@cassandra.apache.org
Date: Fri, 10 Jun 2011 15:24:59 +0000 (UTC)
From: "Jonathan Ellis (JIRA)" <jira@apache.org>
To: commits@cassandra.apache.org
Message-ID: 
 <818915852.10902.1307719499025.JavaMail.tomcat@hel.zones.apache.org>
In-Reply-To: 
 <1760266686.58147.1302800105858.JavaMail.tomcat@hel.zones.apache.org>
Subject: [jira] [Commented] (CASSANDRA-2474) CQL support for compound
 columns
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit


    [ https://issues.apache.org/jira/browse/CASSANDRA-2474?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13047241#comment-13047241 ] 

Jonathan Ellis commented on CASSANDRA-2474:
-------------------------------------------

bq. How about a nested SELECT

That's an interesting idea.

I work best with examples.  So let's take my proposal

{noformat}
SELECT x, y FROM foo:bar WHERE parent='columnA'
{noformat}

and try to come up with a nested-select equivalent.  IMO the most natural would be

{noformat}
SELECT x, y
FROM (SELECT * from foo where id='bar')
WHERE parent='columnA'
{noformat}

My problem with this is that the semantics are completely different than what I would expect from a relational system, and there is no cue telling me to expect that difference other than if I happen to know "nested-selects magically trigger transpose."  As someone with a fairly long relational background this would drive me crazy. :)

More practically, I'd like to provide a single syntax for compound columns in both CQL and HQL (Hive's SQL) on Cassandra.  HQL _does_ support "real" nested selects so trying to figure out when a nested select should transpose vs when it should not seems like a non-starter to me.

> CQL support for compound columns
> --------------------------------
>
>                 Key: CASSANDRA-2474
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-2474
>             Project: Cassandra
>          Issue Type: Sub-task
>          Components: API, Core
>            Reporter: Eric Evans
>              Labels: cql
>             Fix For: 1.0
>
>
> For the most part, this boils down to supporting the specification of compound column names (the CQL syntax is colon-delimted terms), and then teaching the decoders (drivers) to create structures from the results.

--
This message is automatically generated by JIRA.
For more information on JIRA, see: http://www.atlassian.com/software/jira