There is some discussion in this ticket, looks like it was pushed to a later release 

https://issues.apache.org/jira/browse/CASSANDRA-3647?focusedCommentId=13292781&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-13292781

I cannot find any open tickets for it https://issues.apache.org/jira/browse/CASSANDRA-5918?jql=labels%20%3D%20cql%20AND%20status%20in%20(Open%2C%20%22In%20Progress%22)

May be a good idea to create one and request the feature. 

Cheers

-----------------
Aaron Morton
New Zealand
@aaronmorton

Co-Founder & Principal Consultant
Apache Cassandra Consulting
http://www.thelastpickle.com

On 30/10/2013, at 3:24 am, Keith Freeman <8forty@gmail.com> wrote:

There's some rationale here: http://mail-archives.apache.org/mod_mbox/cassandra-user/201305.mbox/%3CCAENxBwx6pcSA=cWn=dKW_52K5odw5F3Xigj-zn_4BwFth+4ruA@mail.gmail.com%3E

And I'm sure part of the reason is the 64k size limit: maps (and sets and lists) are limited to 64k total size (http://wiki.apache.org/cassandra/CassandraLimitations), so it wouldn't be very read-efficient to load individual elements.

On 10/28/2013 08:03 PM, Liam Stewart wrote:
I was wondering if anybody could explain the rationale behind disallowing selection of individual elements from a map in CQL and why an entire map must be retrieved at once when items are stored as distinct columns? Are there any plans to allow individual selection?

--
Liam Stewart :: liam.stewart@gmail.com